WO2010081192A1

WO2010081192A1 - Heat transfer

Info

Publication number: WO2010081192A1
Application number: PCT/AU2010/000027
Authority: WO
Inventors: Darren M. Bates
Original assignee: Cavitus Pty Ltd
Priority date: 2009-01-13
Filing date: 2010-01-13
Publication date: 2010-07-22

Abstract

The present invention relates to methods for enhancing heat transfer into a solid comprising applying heat to a mixture comprising a solid and a liquid, applying highly propagating ultrasonic energy to the mixture wherein the highly propagating ultrasonic energy is uniformly distributed throughout said solid thereby enhancing the transfer of the heat into said solid.

Description

Heat Transfer

Cross-Reference to Related Application

This application claims the benefit of Australian Provisional Patent Application No. 2009900107 filed 13 January 2009 which is incorporated herein by reference in its entirety.

Technical Field

The present invention relates to methods of using highly propagating ultrasonic energy to enhance heat transfer into a solid or liquid, including food, agricultural or non-food products. In particular the invention relates to methods of using highly propagating ultrasonic energy to enhance thermal heat transfer into flow streams containing liquids and/or solids or packaged items, foods, beverages or equipment.

Background

Presently there are a limited number of ways of transferring heat into solids or liquids such as food and beverage equipment or packaged products. Equipment such as heat exchangers, evaporators, pasteurization tubes, retort systems, are used to heat, cook, sterilize or pasteurize. A problem with these types of equipment is that they require extended periods for heat transfer to occur which can negatively impact production rates and food quality due to exposure to elevated temperatures over extended periods. A further problem is that of non uniform heating.

A conventional ultrasonic bath produces ultrasonic energy in the form of a standing wave such that when a solid or liquid is placed in the bath the pattern of heat transfer shows alternating partially heated zones and substantially unheated zones. In order to achieve a greater heat transfer the solid or liquid must be moved relative to the standing wave which can be impractical for large volumes of solid or liquid, large flow streams or large batch volumes. Heat transfer using an ultrasonic bath, while demonstrating some potential use in the cleaning of smaller articles is ineffective in terms of large scale heat transfer.

Furthermore, conventional ultrasonic baths produce energy waves that dissipate very quickly with distance and do not propagate through high density or high percentage solid products. Accordingly there exists a need in the art for methods for enhanced heat transfer into a solid or liquid.

Summary

In a first aspect there is provided a method for enhancing heat transfer into a solid comprising

(i) applying heat to a mixture comprising a solid and a liquid

(ii) applying highly propagating ultrasonic energy at frequency of between about 16 kHz to about 40 kHz to the mixture wherein the highly propagating ultrasonic energy is uniformly distributed throughout said solid thereby enhancing the transfer of the heat into said solid.

In a second aspect there is provided a method for enhancing heat transfer into a liquid comprising

(i) applying heat to the liquid

(ii) applying highly propagating ultrasonic energy at frequency of between about 16 kHz to about 40 kHz to the liquid wherein the highly propagating ultrasonic energy is uniformly distributed throughout said liquid thereby enhancing the transfer of the heat into said liquid.

The method any of the first or second aspect may further comprise the step of applying pressure to the solid or liquid wherein the pressure and highly propagating ultrasonic energy act synergistically to enhance transfer of heat into said solid or liquid.

In a third aspect there is provided a method for cooking a food comprising

(i) applying heat to the food

(ii) applying highly propagating ultrasonic energy at frequency of between about 16 kHz to about 40 kHz to the food wherein the highly propagating ultrasonic energy is uniformly distributed throughout said food thereby enhancing the transfer of the heat into said food.

The method may further comprise the step of applying pressure to the food wherein the pressure and highly propagating ultrasonic energy act synergistically to transferring enhances heat transfer from the liquid into the food.

The cooking apparatus may be a fryer, steamer, microwave oven, radio frequency oven electric or gas oven, retort cooker or boiling apparatus. In a fourth aspect there is provided a method for pasteurisation of a solid or a liquid comprising

(i) applying heat to the solid or liquid

(ii) applying highly propagating ultrasonic energy at frequency of between about 16 kHz to about 40 kHz to the solid or liquid wherein the highly propagating ultrasonic energy is uniformly distributed throughout said solid or liquid thereby enhancing the transfer of the heat into said solid or liquid.

The method may further comprise the step of applying pressure to the solid or liquid wherein the pressure and highly propagating ultrasonic energy act synergistically to transfer heat into the solid or liquid.

The enhanced heat transfer may enhance reduction of microbiological load.

In a fifth aspect there is provided a method for producing a low moisture content spray dried powder from a liquid or slurry using a spray drying apparatus comprising

(i) contacting at least a portion of said spray drying apparatus with a highly propagating ultrasonic energy emitting assembly; and

(ii) operating the spray drying apparatus wherein the liquid or slurry is vapourised and;

(iii) applying highly propagating ultrasonic energy at frequency of between about 16 kHz to about 40 kHz wherein the highly propagating ultrasonic energy is uniformly distributed throughout the vapourised liquid or slurry and wherein the highly propagating ultrasonic energy enhances heat transfer into the liquid or slurry thereby decreasing the moisture content of the spray dried powder.

The method may further comprise the step of applying pressure to the liquid or slurry wherein the pressure and highly propagating ultrasonic energy act synergistically to transfer heat into the liquid or slurry.

In a sixth aspect there is provided a method for cooling a solid or a first liquid comprising

(i) contacting at least a portion of said solid or first liquid with a highly propagating ultrasonic energy emitting assembly; and

(ii) contacting at least a portion of said solid or first liquid with a volume of a second liquid at a temperature lower than the solid or first liquid

(iii) applying highly propagating ultrasonic energy at frequency of between about 16 kHz to about 40 kHz wherein the highly propagating ultrasonic energy is uniformly distributed throughout the solid or first liquid and wherein the highly propagating ultrasonic energy enhances heat transfer from the solid or first liquid into the second liquid, thereby cooling the solid or first liquid.

The first liquid may be in a container.

The method may further comprise the step of applying pressure to the solid or liquid wherein the pressure and highly propagating ultrasonic energy act synergistically to transfer heat into the second liquid.

The frequency of the highly propagating ultrasonic energy may be the resonant frequency of the solid, liquid, slurry or food product.

The container may be a heat exchanger, evaporator, deaerator, deoudoriser, degassing apparatus, pasteuriser, tank, pipe, coil or spray drier.

The method may further comprise the step of deaerating, degassing, deodourising or cooling the enhanced heat transfer product.

The application of highly propagating ultrasonic energy into the product may generate cavitation in the product. The cavitation may generate heat in the product.

In a seventh aspect there is provided a method of enhancing heat transfer through a solid surface of a container and into a solid or liquid inside the container, the method comprises

(i) applying heat to the surface

(ii) attaching a high power transducer or sonotrode to the surface

(iii) applying highly propagating ultrasonic energy from the transducer or sonotrode across the surface wherein the transducer or sonotrode vibrates at a frequency of between about 16 KHz and about 500 KHz and wherein the highly propagating ultrasonic energy enhances heat transfer across and through the surface and into the solid or liquid or materials inside the surfaces or boundaries.

In one embodiment the sonotrode may be immersed in a coupling liquid wherein the coupling liquid is in contact with the container.

The solid or liquid inside the container may be a flow stream comprising liquid and/or solid components.

The transducer may include a vibration direction conversion member.

The frequency of the highly propagating ultrasonic energy may be between about 16 KHz and about 40 KHz. The temperature of the liquid may be between about 20⁰C and about 500⁰C. The surface may be the surface of a heat exchanger, cooker, retort cooker, pasteuriser, fryer, tank, bottle, can, bag, sachet or any combination thereof.

In one embodiment the highly propagating ultrasonic energy facilitates the transfer heat through the surface and into the liquid or solid.

In an eighth aspect there is provided a method for enhancing heat transfer into a solid comprising

(i) applying heat to a mixture comprising a solid and a liquid

(ii) applying highly propagating ultrasonic energy to the mixture wherein the highly propagating ultrasonic energy is uniformly distributed throughout said solid thereby enhancing the transfer of the heat into said solid.

In a ninth aspect there is provided method for enhancing heat transfer into a liquid comprising

(i) applying heat to the liquid

(ii) applying highly propagating ultrasonic energy to the liquid wherein the highly propagating ultrasonic energy is uniformly distributed throughout said liquid thereby enhancing the transfer of the heat into said liquid.

In a tenth aspect there is provided method for cooking a food comprising

(i) applying heat to the food

(ii) applying highly propagating ultrasonic energy to the food wherein the highly propagating ultrasonic energy is uniformly distributed throughout said food thereby enhancing the transfer of the heat into said food.

In an eleventh aspect there is provided a method for pasteurisation of a solid or a liquid comprising

(i) applying heat to the solid or liquid

(ii) applying highly propagating ultrasonic energy to the solid or liquid wherein the highly propagating ultrasonic energy is uniformly distributed throughout said solid or liquid thereby enhancing the transfer of the heat into said solid or liquid.

In an twelfth aspect there is provided a method for producing a low moisture content spray dried powder from a liquid or slurry using a spray drying apparatus comprising

(ii) operating the spray drying apparatus wherein the liquid or slurry is vapourised and; (iii) applying highly propagating ultrasonic energy wherein the highly propagating ultrasonic energy is uniformly distributed throughout the vapourised liquid or slurry and wherein the highly propagating ultrasonic energy enhances heat transfer into the liquid or slurry thereby decreasing the moisture content of the spray dried powder.

In an thirteenth aspect there is provided a method for cooling a solid or a first liquid comprising

(iii) applying highly propagating ultrasonic energy wherein the highly propagating ultrasonic energy is uniformly distributed throughout the solid or first liquid and wherein the highly propagating ultrasonic energy enhances heat transfer from the solid or first liquid into the second liquid, thereby cooling the solid or first liquid.

In an embodiment of any one of the eighth to thirteenth aspects the frequency of the highly propagating ultrasonic energy may be between about 10 KHz and about 2000 KHz or between about 10 KHz and about 1500 KHz, or between about 10 KHz and about 1000 KHz, or between about 10 KHz and about 750 KHz, or between about 10 KHz and about 400 KHz, or between about 10 KHz and about 250 KHz, or between about 10 KHz and about 125 KHz, or between about 10 KHz and about 100 KHz, or between about 10 KHz and about 60 KHz, or between about 10 KHz and about 40 KHz, or between about 10 KHz and about 30 KHz, or between about 10 KHz and about 20 KHz, or between about 16 KHz and about 40 KHz, or between about 10 KHz and about 30 KHz, or between about 16 kHz and about 26kHz or between about 19 KHz and about 28 KHz, or between about 16 KHz and about 22 KHz, or between about 16 KHz and about 20.0KHz.

Definitions

The terms "highly propagating radial energy" and "highly propagating ultrasonic energy" are used interchangeably to refer to energy emitted substantially orthogonal to the axial direction of the sonotrode or transducer.- The term "comprising" means including principally, but not necessarily solely. Furthermore, variations of the word "comprising", such as "comprise" and "comprises", have correspondingly varied meanings.

As used in this application, the singular form "a", "an" and "the" include plural references unless the context clearly dictates otherwise. For example, the term "a surface" also includes a plurality of surfaces.

As used herein, the term "synergistic" refers to a greater than additive effect that is produced by a combination of two entities. A synergistic effect exceeds that which would be achieved by combining the effect of each entity taken alone.

As used herein, the term "solid" refers to a substance having a shape and volume and which is neither liquid nor gaseous. A solid may therefore be porous or permeable.

As used herein "enhanced" refers to an effect that is greater than the same effect without the application of highly propagating ultrasonic energy.

Detailed Description

The skilled person will understand that the figures and examples provided herein are to exemplify, and not to limit the invention and its various embodiments.

Conventional ultrasonic apparatus may be used to enhance heat transfer to a solid or liquid but suffer from a number of disadvantages. For example, the use of conventional ultrasonic energy produced in a conventional apparatus creates standing waves in the product filling the apparatus so that the product will show zones of enhanced heat transfer or in areas not bounded by the standing waves and zones where heat transfer is enhanced in the regions bounded by the standing waves.

As mentioned above conventional ultrasonic cleaning bath technology/transducers are based on the formation of standing wave technology. Standing waves do not penetrate into products as the energy levels are very low. Similarly standing waves do not enhance liquid heat transfer. Furthermore the formation of standing waves results in areas exposed to the standing waves and areas that are not exposed, typically giving a 50% dead zone. Thus, in a solid product, the result may be that only 50% of the product has enhanced heat transfer.

Further, conventional systems produce energy waves that dissipate very quickly with distance and do not affect the liquid heat transfer properties of a fluid and little if any possibility of enhancing heat transfer into a solid. For example, a conventional sono trade experiences a drop in energy of 95% over 10mm from the sonotrode in a product with 30% solid material, with negligible penetration into surrounding material. The treated zone from these waves produced is not effective across a large volume of product that is cavitation occurs in some areas and not in others.

In accordance with the present invention methods for applying highly propagating ultrasonic energy to enhance heat transfer into a liquid and/or a solid are provided. The methods of the invention generally comprise the application of highly propagating ultrasonic energy to a product to enhance heat transfer into a liquid and/or a solid. The solids may be solid or semi solid food or non-food products including agricultural products. The solids may also be products formulated for human or animal consumption

The use of highly propagating radial energy waves has substantial improvements over existing ultrasonic technology and sonotrode systems that until now has not been exploited, for example:

1. significantly enhanced working/travel distance of energy waves

2. high energy to change molecular structure

3. ability to penetrate through solid boundaries and surfaces

4. uniform distribution of energy waves

5. enhance convective liquid transfer

Highly propagating ultrasonic energy

A sonotrode generates ultrasonic energy typically when an alternating voltage is applied across a ceramic or piezoelectric crystalline material (PZT). The alternating voltage is applied at a desired oscillation frequency to induce movement of the PZT. The PZT transducer is mechanically coupled to the horn means which amplifies the motion of the PZT. The horn means includes a tip portion, referred to herein as a sonotrode. The assembly of the PZT horn means including the tip portion may also be referred to herein as the sonotrode. Highly propagating ultrasonic energy or HPU includes ultrasonic energy that is emitted substantially orthogonal to the axial direction of a sonotrode. Such energy propagates through a fluid medium, typically water or a gas and over a large distance from the sonotrode and is not limited to the areas immediately surrounding the sonotrode. After propagating through the medium the highly propagating ultrasonic energy may be applied over a surface and to penetrate into said surface.

Highly propagating ultrasonic energy waves are able to propagate across through a viscous product up to a distance of at least 50cm to about 300cm, or about 100cm to about 300cm or about 150cm to about 300cm or about 200cm to about 300cm to a contaminated surface. Highly propagating ultrasonic energy propagates substantially uniformly across volumes leaving and are able to penetrate up to up to a depth of about 0.0001 -lmm, or about l-20mm, or up to a depth of about 2-20mm or up to a depth of about 5-20mm or up to about 5-15mm or up to about 7-10mm into substantially solid, porous or colloidal components of a product.

In one embodiment of the present invention a combination of the high power, low frequency, long wavelength and sonotrode shape/design allows for the above effects to take place. In contrast, ultrasonic energy emitted from conventional ultrasonic cleaners has limited propagation distance from the emitting surface with a drop in energy of 90+ % at a distance of 100 cm and are not uniform in their volume area or volume of the treated flow stream, and do not have the ability to penetrate into solid, porous or colloidal components of a product.

In another embodiment, the sonotrode may be arranged such that the highly propagating ultrasonic energy generated is able to propagate through a viscous product up to a distance of about 50cm to about 300cm, or about 100cm to about 300cm or about 150cm to about 300cm or about 200cm to about 300cm to the inner surface of a flow cell, conduit, vessel containing the viscous fluid, transmit uniformly throughout the whole volume leaving no single space/zone untouched from the wave energy. In addition, the highly propagating radial waves are able to penetrate up to about 5-20mm or up to about 5-15mm or up to about 7-10mm or into solid, porous or colloidal components of a product suspended in the viscous flow stream or material.

In yet another embodiment, the highly propagating ultrasonic energy is emitted substantially at a right angle from the surface of a sonotrode with high energy. In this context high energy refers to a less than about 20% drop in energy and production of shear forces resulting from collapsing cavitation bubbles at a distance of about 100 to about 300cm from the emitting sonotrode. Furthermore, in this context high energy refers to the ability of the highly propagating ultrasonic energy to propagate into solid, porous or colloidal components of a product and create cavitation internally up to a depth of about 0.0001-lmm, or aboutl-20mm, or up to a depth of about 2-20mm or up to a depth of about 5-20mm or up to about 5- 15mm or up to about 7- 10mm.

While not being limited by theory it is generally held that highly propagating ultrasonic energy enhances heat transfer and also via generating cavitation. Cavitation comprises the repeated formation and implosion of microscopic bubbles. The implosion generates high-pressure shock waves and high temperatures near the site of the implosion. As a result, the energy waves from collapsing cavitation bubbles causes the heat energy to accelerate at very high speed, through boundaries such as packaging materials or surfaces of food substrates and enhance the penetration into a solid substrate. The enhanced heat transfer and penetration into the solid substrate can occur without affecting the physical surface of the outer boundary layer.

In one embodiment the ultrasonic emitting assembly or ultrasonic generator generates ultrasonic energy at frequencies between about 10 KHz and about 2000 KHz or between about 10 KHz and about 1500 KHz, or between about 10 KHz and about 1000 KHz, or between about 10 KHz and about 750 KHz, or between about 10 KHz and about 400 KHz, or between about 10 KHz and about 250 KHz, or between about 10 KHz and about 125 KHz, or between about 10 KHz and about 100 KHz, or between about 10 KHz and about 60 KHz, or between about 10 KHz and about 40 KHz, or between about 10 KHz and about 30 KHz, or between about 10 KHz and about 20 KHz, or between about 16 KHz and about 40 KHz, or between about 10 KHz and about 30 KHz, or between about 16 kHz and about 26kHz or between about 19 KHz and about 28 KHz, or between about 16 KHz and about 22 KHz, or between about 16 KHz and about 20.0KHz.

For example, the amplitude of the highly propagating ultrasonic energy is between about 0.001 to about 500 microns, preferably between about 0.01 to about 40 microns amplitude, even more preferably between about 1 to about 10 microns.

For example, the energy density of the highly propagating ultrasonic energy is between about of 0.00001 watt/cm³ to 1000 watt/cm³, between about 0.0001 watt/cm³ to about 100 watts/cm³, hi a preferred embodiment high power and high amplitude highly propagating ultrasonic energy (O.OOOOlW/cm² - lOOW/cm²) and 0.001-micron- 500-microns (for example 0.0001 to 50 w/cm³ and amplitude range would be 0.01 - 20 microns for enhanced thermal heat transfer) may be used. The highly propagating ultrasonic energy may be applied to solids or liquids at an average specific energy between IxIO^"10 kWh and IxIO^"1 kWh ultrasonic energy, more preferably between 1x10^"8 kWh and 1x10^"4 kWh ultrasonic energy.

The highly propagating ultrasonic energy may be applied at a frequency between about 16 KHz and about 40 KHz, or between about 16 KHz and about 20 KHz and at an energy density of between about 0.00001 watt/cm³ to 1000 watt/cm³ or between about 0.0001 watt/cm³ to about 100 watts/cm³. In a preferred embodiment the highly propagating ultrasonic energy may be applied at a frequency between about 16 KHz and about 20 KHz and at an energy density of about 0.0001 watt/cm³ to about 50 watt/cm³.

In another embodiment the highly propagating ultrasonic energy may be applied in combination at a frequency between about 16 KHz and about 40 KHz, or between about 16 KHz and about 20 KHz and at an amplitude of between 0.001- microns to about 500 microns. In a preferred embodiment the highly propagating ultrasonic energy may be applied at a frequency between about 16 KHz and about 20 KHz and at an amplitude of between 0.01-micron to about 20 microns.

In a further embodiment the highly propagating ultrasonic energy may be applied at a frequency between about 16 KHz and about 40 KHz, or between about 16 KHz and about 20 KHz and at an amplitude of between 0.001-microns to about 500 microns and at an energy density of between about 0.00001 watt/cm³ to 1000 watt/cm³ or between about 0.0001 watt/cm to about 100 watts/cm . hi a preferred embodiment the highly propagating ultrasonic energy may be applied at a frequency between about 16 KHz and about 20 KHz and at an amplitude of between 0.01-micron to about 20 microns and at an energy density of about 0.0001 watt/cm³ to about 50 watt/cm³.

In another embodiment the highly propagating ultrasonic energy is applied to a fluid, food product, or a flow able material or fluid over a period of time from about 0.001 second to about 60 minutes, or from about 0.001 second to about 50 minutes, or from about 10 seconds to about 40 minutes, or from about 15 seconds to about 40 minutes, or from about 20 seconds to about 30 minutes, or from about 25 seconds to about 20 minutes, or from about 30 seconds to about 10 minutes, or from about 30 seconds to about 2 minutes or from about 0.001 second to about 1 minute or from about 0.001 second to about 10 seconds, or from about 0.001 second to about 1 second or from about 0.001 second to about 0.1 second, from about 0.001 second to about 0.01 second. Enhanced heat transfer

Highly propagating ultrasonic energy may be used to enhance heat transfer into a liquid or a solid. Typically such a method includes the application of highly propagating waves across and through multiple surfaces. For example a solid may be immersed into a coupling liquid which is in contact with an ultrasonic sonotrode.

While not being bound by a particular theory it is believed the method works by the action of microscopic cavities collapsing and releasing shock waves, a process known as cavitation. The microscopic cavities are formed by sending highly propagating ultrasonic energy into a fluid that is in contact with the product.

Enhanced heat transfer into liquids into solids such as food, agricultural or non-food products is typically achieved by using an automatic frequency scanning system for different types of equipment. For example, the type of surface (shape, dimensions, type of material), thickness or number of surfaces and type of contamination will determine the resonance frequency of that equipment. The ultrasonic resonance frequency is the frequency at which the ultrasonic unit will deliver the greatest energy efficiency.

The resonance frequency of a solid or liquid is the frequency of the solid or liquid at which it oscillates at larger amplitude and power/efficiency compared to other frequencies. At the resonant frequency periodic driving forces (such as the application of highly propagating ultrasonic energy) can produce large amplitude oscillations. While the application of highly propagating ultrasonic energy to a solid or liquid enhances heat transfer, if the frequency of the highly propagating ultrasonic energy is matched to the resonance frequency of the solid or liquid heat transfer will be more efficient and occur to a greater degree than at other frequencies.

The methods described herein are particularly suited for use with an ultrasonic system, which locks onto the resonance frequency of a specific type of equipment and then re-scans for the new resonance frequency every 0.001 second throughout the treatment process. Without resonance frequency tracking a variation as little as 10Hz from the resonance frequency would result in a drop in energy efficiency in the order of 10 - 40%. This has a significant reduced effect on the enhanced heat transfer.

By way of example, the resonance frequency of a retort vessel is 20,850 Hz where as an evaporator tube will have a resonance frequency of 20,560 Hz. Conventional devices using transducers welded/bolted to the outside of vessels/chambers/tubes were not designed with an automatic resonance frequency tracking system for specific types of organic equipments so equipments could not be processed at the correct resonance frequency and maximum power efficiency.

Highly propagating ultrasonic energy in combination with pressure may be used to facilitate enhanced heat transfer. The pressure may be between about 0.1 bar and about 10 bar or between about 0.5 bar and about 5 bar or between about 1 bar and about 3 bar.

Highly propagating ultrasonic energy in combination with heat (40-250°C) may be used to facilitate enhanced heat transfer. The temperature may be between about 3O⁰C and about 25O⁰C, or between about between about 35⁰C and about 200⁰C, or between about 4O⁰C and about 175⁰C, or between about 4O⁰C and about 15O⁰C, or between about 4O⁰C and about 125⁰C, or between about 4O⁰C and about 100⁰C, or between about 4O⁰C and about 75⁰C.

Highly propagating ultrasonic energy may be used to enhance the heat transfer in fluids or mediums such as aqueous liquids or gases, oils, non-aqueous liquids, steam, gases. Other materials could also be used to aid as the coupling medium to transfer of heat using ultrasound such as rubber, thermoplastic materials, metal, polymers, resins.

Low frequency/high intensity highly propagating ultrasonic energy in combination with low temperature fluids or gases may be used to enhance cooling by enhancing heat transfer through surfaces, packaging materials or into solid substrates such as food and beverage products.

As noted above existing sonotrode technology, such as that found in ultrasonic baths, produces waves of very limited propagation distance, very localised and no possibility of penetration into viscous or high % solid materials. These systems produce energy waves that dissipate very quickly with distance and do not affect the heat transfer properties of a fluid and the convective heat transfer properties. For example, a conventional sonotrode experiences a drop in energy of approximately 95% over 10mm in 30% solid matrix from the sonotrode, with negligible penetration into surrounding material. Conventional sonotrodes do not emit waves, but rather only produce localised cavitation, so there is no mechanism for transferring the heat energy through solid boundaries. Conventional ultrasonic cleaning technology is based on the formation of standing wave technology. Standing waves do not have the ability to penetrate uniformly across and through surfaces, the energy levels are very low and thus they do not enhance heat transfer across and through surfaces of equipment or packaging materials. The nature of standing waves means that there are bands of active areas and bands of dead zone, where no effect of the ultrasonic energy is evident. Typically in the order of 50% of a surface exposed to a standing wave is not affected by the wave.

In one embodiment the transfer of heat to a food product may be enhanced by the application of highly propagating ultrasonic energy.

Synergistic effect of highly propagating ultrasonic energy and other technologies or agents for enhancing heat transfer.

As disclosed herein the application of highly propagating ultrasonic energy to a solid or liquid results in enhanced heat transfer into that liquid or solid. Surprisingly, the application of highly propagating ultrasonic energy to a solid together with conventional methods of heat transfer results in enhanced heat transfer than would be expected merely from the additive effects of conventional methods and the application of highly propagating ultrasonic energy. That is, there is a synergistic effect between the application of highly propagating ultrasonic energy to a solid or liquid and the use of conventional methods of heat transfer. This synergism results in enhanced heat transfer.

The conventional methods enhancing of heat transfer include homogenisation, application of pressure and mixing.

The highly propagating ultrasonic energy is preferably applied to the reaction mixture at an average specific energy between 1x10^"7 kWh and 1x10^" kWh ultrasonic energy per liter reaction mixture, more preferably between IxIO^"4 kWh and IxIO^"2 kWh ultrasonic energy per liter reaction mixture. Low frequency/high intensity ultrasound in combination with mild heat (O⁰C - 90⁰C) may also be used to enhance heat transfer.

A method of enhancing heat transfer into an item is provided. The method includes the steps of heating the item in a liquid and applying highly propagating ultrasonic energy into the liquid with a ultrasonic sonotrode, the ultrasonic sonotrode characterised in that it vibrates at a frequency of between 16 KHz and 100 KHz, the sonotrode characterised in that it emits a radial energy wave relative to the sonotrode. In a preferred embodiment the heat and the highly propagating ultrasonic energy act synergistically.

Low frequency/high intensity highly propagating ultrasonic energy in combination with pressure (0.5 to 500 bar pressure but preferentially between 2 and lObar) may be used enhance heat transfer into liquid components. This synergistic effect between ultrasonic energy and pressure greatly enhances the coupling and impedance matching of the ultrasonic waves through surface particularly when the surface contains high solids content. The improved coupling of the waves to the equipment enhances heat transfer.

Fore example, the application of highly propagating ultrasonic energy and pressure may act synergistically to increases the flow rate required to evaporate a flow stream of infant formula to increase the solids content. Highly propagating ultrasonic energy may be applied, for example from a sonotrode in the flow stream. Alternatively or additionally a highly propagating ultrasonic energy emitting assembly may be connected to an evaporator tube system. The heat energy generated by the steam in the evaporator is transferred through the steel tubing surface of the evaporator tube into the fluid stream. The method may further comprise continuous or intermittent application of pressure.

The application of either highly propagating ultrasonic energy alone or pressure alone increases the flow rate which allows evaporation to increase the solids content. The additive effects highly propagating ultrasonic energy and pressure would be expected to result in an increase in flow rate which allows evaporation to increase the solids content. However, the highly propagating ultrasonic energy and pressure may act synergistically to produce a greater increase in flow rate which allows evaporation to increase the solids content, than would be expected from the additive effects highly propagating ultrasonic energy and pressure.

In one embodiment the flow rate required to evaporate a flow stream to increase the solids content may be increased by about 2% to about 90%, or by about 5% to about 80%, or by about 7% to about 60%, or by about 10% to about 40%, or by about 15% to about 30% of the flow rate required in the absence of the application of highly propagating ultrasonic energy. Products

As would now be apparent to those skilled in this art, the methods of heat transfer described herein may be applied to food processing equipment such as evaporators, pasteurizers, heat exchangers, cookers, fryers, steam injection cookers, spray dryers, microwaves, retorts, beer and wine processing and manufacturing equipment and non-food based equipment (chemical, pharmaceutical, polymer, petroleum, water equipment).

The methods of heat transfer described herein may be applied to solids or liquid products.

The liquids may be water, oil, fruit juices, vegetable juices, skimmed milk, low fat milk, whole fat milk, cream, low fat cream, low fat yogurt, yogurt ,dairy based beverages, liquid coffee, syrups, sugar syrups.

The oil may be soya bean oil, vegetable oil, corn oil, cotton seed oil, nut oil, citrus peel oil.

In some embodiments the solid may be a food product, an agricultural or nonfood products.

The methods of described herein may be applied to a variety of food products, grains, hydrocolloids, dairy products, soy proteins, vegetable materials, agricultural products

The grains of fibres thereof may be selected from the group comprising oats, barley, wheat, corn, maize, rye and rice. The grains may also be pulses including chickpea, faba/broad bean, field pea, lentil, lupin, vetch, mungbean, azuki bean, soya bean, navy bean, cowpea and pigeon pea.

The hydrocolloid materials may be selected from the group comprising gelatin, starch, xanthan gum, carrageenan, pectin, gum arabic, guar gum, alginates, seaweed powder or combinations of such hydrocolloids.

The soya protein may be a soya protein isolate.

The dairy products may be selected from the group comprising dairy proteins, whey protein, skimmed milk powder, low fat milk powder, whole fat milk powder, yogurt, butter, margarine and caseinates.

The vegetable materials may include pulp, pomace, fibre, skins, whole vegetables selected from the group comprising carrot, tomato, onion, garlic, cabbage, broccoli, cauliflower, sweet potato, potato, peas, beans, celery, herbs , pumpkin, capsicum, mushrooms or combinations of, fruit based materials (pulp, pomace, fibre, skins, whole fruit, sliced fruit) such as apples, oranges, grapes, apricots, pears, strawberry, raspberry, blueberry, blackberry, lemons, limes, grapefruit, rhubarb, plums, cherries, kiwi fruit, lychees, cranberries pomegranate, banana, figs, ginger, or combinations thereof, oil seeds such as palm fruit, canola, soya beans, olives, sunflower, coconut, cocoa beans, coffee beans, ground cocoa, ground coffee, powder chocolate and coffee, instant coffee, tea leaf and ground tea, green tea, herbal tea (peppermint, chamomile, rose hip,).

The food product may be selected from the group comprising wheat flour, sugar, confectionery products, dextrose, bread, dough based materials, bakery products, cakes, snack foods such as pretzels, fried or baked or microwaved potato chips, crisps, snacks or chips, crisps, snacks comprising fruits or vegetables or combinations thereof, breakfast cereal products such as corn flakes, oat flakes, rice flakes or bubbles, oat flakes, muesli, wheat flakes, bran flakes, or combinations of or muesli bars, cereal bars, extruded cereal products, dried fruit or dried fruits in combination with cereal products, cooked or non cooked meats such as beef, lamb, chicken, turkey, pork, mutton, deer, ham, or combinations of, seafood and fish such as salmon, tuna, sardines, crab, cod, snapper, trout, mackerel, perch, squid, oysters, scallops, crayfish, lobster, hops, yeast, malted barley, pickled food products, egg powder or products containing egg, salt, ground herbs and spices, products contained in packaged/canned/bottled soups, or products contained in packaged/canned/bottled sauces or canned/packaged/bottled fruit or vegetable products or canned/packaged/bottled beverage products or any combination of the above in the manufacture of any food or beverage product.

The food product may be packaged, canned or bottled soups, or packaged, canned, bottled sauces, fruit or vegetable products or any canned, packaged or bottled beverage products or any combination of the above used in the manufacture of any food or beverage product.

The agricultural product may be selected from the group comprising agricultural feedstock material for example for fermenting and making ethanol, or agricultural feedstock material for making biodiesel fuel, sugar cane and sugar beet.

The non-food products may include clay, clay-based materials, paper and timber based pulps, mineral powders and mineral mining ores, plastic materials, foam materials, materials used in the manufacture of pharmaceutical products or any inorganic, organic, mineral material including mineral particles such as those found in mining slurry or gypsum slurry, health care products such as shampoo, conditioners, cleaning liquids and powder detergents, make up beauty products, body and facial creams.

Apparatus

In a preferred equipment design, this present invention relates to the use of radial sonotrodes, which emit high-energy ultrasonic waves. However, other sonotrodes could be used such as high amplitude focused sonotrodes, which can be screw bolted or strapped on to the outside of equipment to generate energy wave vibration which enhances thermal transfer.

The sonotrode arrangements in accordance with the present invention are based on using transducers attached to the outside of equipment or radial sonotrodes immersed in a liquid phase and capable of being tuned to frequencies in the range of 16kHz - 50OkHz and produce energy intensities of between 0.0001 to 1000 W/cm³.

Another suitable arrangement utilizes radial sonotrodes fitted into equipment to enhance thermal heat transfer.

An ultrasonic heating apparatus is provided which includes an ultrasonic sonotrode, wherein the ultrasonic sonotrode vibrates at a frequency of between 16 KHz and 100 KHz and emits a substantially radial energy wave relative to the sonotrode. The apparatus also comprises a heating bath for immersion of item to be heated. The sonotrode is operatively connected to the heating bath so that when in use the item is subjected to heat energy from the heating bath simultaneously with highly propagating ultrasonic energy emitted from the sonotrode. The use of apparatus are illustrated herein. For example, with reference to Figure 1 a product enters a flow cell 10 at A and exits the flow cell 10 at B. During the passage through the flow cell highly propagating ultrasonic energy is emitted from the sonotrode 14 and is applied directly to the product. The highly propagating ultrasonic energy generates cavitation in the product. The high shear energy waves created by the collapsing cavitation bubbles enhance the heat transfer into the product.

With reference to Figure 2 the enhanced heat transfer during the passage through the flow cell as highly propagating ultrasonic energy is applied to the product by the flow cell which is connected to the highly propagating ultrasonic energy generator 18 via a transducer 22 and a booster means 26. The heat transfer into a product is similarly enhanced by the operation of the apparatus illustrated in Figure 3 except that the highly propagating ultrasonic energy is indirectly transferred into the reaction mixture from the sonotrode 14 via a suitable heated fluid medium 30 to the flow cell 10. The heated fluid medium may be for example water or oil. The product passes through A into the flow cell 10 and exits the flow cell 10 through B. A highly propagating ultrasonic energy generator 18 is connected to a transducer 22 which is further connected via a booster horn 26 to the sonotrode 14.

With reference to Figure 4 a method of clarifying a product by centrifugation is provided. The method comprises the application of highly propagating ultrasonic energy to that product in the flow cell 10 to enhance the heat transfer into the product and change its viscosity. On exiting the flow cell 10 the product, now with reduced viscosity, is centrifuged and the solid or heavy phase separated from the liquid or light phase of the product. As sedimentation of solids or a heavy phase of a product is influenced by the viscosity of the product the reduced viscosity after application of highly propagating ultrasonic energy enables more efficient separation of the liquid phase from the heavy or solid phase by centrifugation.

It will be understood by the skilled addressee that the centrifuge may, as illustrated, be a continuous centrifuge connected to the outflow of the flow cell but in another embodiment is a batch centrifuge with no direct connection to the flow cell. The enhanced heat transfer to reduce viscosity of product may be stored before centrifugation.

With reference to Figure 5 when the product enters the flow cell 10 highly propagating ultrasonic energy is applied to the product to reduce its viscosity. After exiting the flow cell 10 the product, now with reduced viscosity, enters a heat exchanger 46.

The flow of fluids, such as the feed product illustrated in Figure 5, is generally laminar and mixing does not occur to any great extent due to flow action. Because of this heat transfer from a laminar flow occurs mostly by heat conduction through the product. Additionally, fluids often adhere to the surfaces and form a layer thus fouling equipment such as heat exchangers and decreasing the efficiency of heat flow. Therefore by enhancing the heat transfer of the product either temporarily or permanently by application of highly propagating ultrasonic energy more efficient heat exchange can occur in conventional heat exchangers such as illustrated in Figure 5. Alternatively, a transducer can be clamped to the heat exchanger plate and the transfer of heat into the fluid can be enhanced directly.

As illustrated in Figure 5 highly propagating ultrasonic energy may optionally be applied to the heat exchanger 46, typically to reduce fouling, before recovery of the product.

Products used in this method include soy protein, biofuels, vegetable oils and bioplastics or agricultural materials or extracts from agricultural materials, dairy products. Exchanging from these products using this method provides increased production rates, reduced energy costs for production, reduced wastewater production and improved product quality.

With reference to Figure 6 a method of deaeration, deodourising or cooling a product is provided. When the product enters the flow cell 10 highly propagating ultrasonic energy is applied to the product to enhance the heat transfer before the product enters a deaerator, deodouriser or flash cooler 50. As the product is heated more efficiently, deaeration/deodourising process as well as heat transfer from a product is enhanced by the application of highly propagating ultrasonic energy increasing the efficiency and thus reduces energy costs for deaeration, deodourising and cooling processes.

Products used in this method include soy protein and vegetable oils. Reducing the viscosity of these products provides increased yields, improved product quality and material cost savings.

The invention also provides a method of pasteurising and dispensing a beverage or liquid food product. With reference to Figure 7 where a beverage or liquid food enters a pasteurization tube 10 with a transducer connected, the enhanced heat transfer into the product is enhanced by application of highly propagating ultrasonic energy to the product while in the tube. The product is held in the pasteurizer while highly propagating ultrasonic energy increases the efficiency of heat transfer during pasteurisation and thus decreases pasteurisation time or reduces fouling/burn on or increases microbiological kill or enzyme kill/elimination (better degree of pasteurization). By way of example, orange juice pasteurized at 75⁰C for 2 minutes holding time gives a 4.5 log reduction in total microorganism plate count. Enhanced heat transfer of the same orange juice by application of highly propagating ultrasonic energy during pasteurization at 75⁰C for 2 minute holding time a 5.8 log reduction in total microbiological plate count is evident. This is an improved reduction of total microbiological plate count of 1.3 log. Pasteurizing the same orange juice after highly propagating ultrasonic energy combined treatment pasteurizing for 1 minute 35 seconds at 75⁰C gives a 4.6 log reduction in total microbiological plate count which is similar to a 2 minute pasteurisation treatment without the enhanced ultrasonic heat transfer effect.

Products used in this method include carbonated beverages, non carbonated beverages, fruit juice, milk, milk products, sauces, pet food, baby food and canned food, infant formula milk, tomato sauce. Pasteurising and dispensing these products using this method provides increased production rates, reduced energy costs, enhanced microbiological reduction performance, improved product quality, taste and texture, reduced fouling, better heat transfer, increase yield and less waste.

A person skilled in the art will appreciate that these advantages are the result of enhanced thermal heat transfer of the product as a result of the application of highly propagating ultrasonic energy.

A method of filtering is also provided. With reference to Figure 8 the method comprises application of highly propagating ultrasonic energy to the material to be filtered while in passage through a flow cell 10 to enhance the heat transfer into the solid. After exiting the flow cell 10 the solid enters a filter means 62.

In one embodiment highly propagating ultrasonic energy may be applied to the filter during filtration to enhance the heat transfer.

It will be understood by the skilled addressee that the filter may, as illustrated in Figure 10 be connected to the transducer 10. In another embodiment the filter may have no direct connection to the transducer.

The filter may be any filter known in the art including a reverse osmosis filter, a microfilter or and ultrafϊlter or cross flow steel or polymer membrane filter, ceramic filter, steel screen or polymer screen filter, any filters known in the art which have pore sizes ranging from 1000 microns in size down to 0.0001 microns in size.

Products used in this method include dairy protein, vegetable/agricultural oils, soya proteins, grape juice, fruit juices. Reducing the viscosity of these products provides increased production rates and reduced fouling kinetics.

The invention further provides a method for dispensing molten product. With reference to Figure 9 the method comprises the application of highly propagating ultrasonic energy to a molten product in a flow cell 10 to enhance the heat transfer into the molten product. After exiting the exiting the flow cell 10 the product is dispensed via a dispensing means 58 such as filling nozzles. In one embodiment the molten product is dispensed into moulds.

With reference to Figure 4 a radial sonotrode 41 is present in a closed container such as a retort 44 at least partially filled with a liquid. The liquid may be heated to a desired temperature. The highly propagating ultrasonic energy 42 produced by the radial sonotrode 41 penetrate the containers 43 and enhance the transfer of heat in the liquid into the containers 43 and their contents. The containers may be a can or bottle, but may also be a food product to be heated.

The sonotrodes/transducers can be mounted or retrofitted to food/agricultural equipment, tanks, vessels (round, square, oval), troughs, pipes, flow-cells containing the contamination.

The present invention will now be further described in greater detail by reference to the following specific examples, which should not be construed as in any way limiting the scope of the invention.

Examples

Example 1: Comparison of heat transfer using conventional ultrasound and highly propagating ultrasonic energy.

The effect of highly propagating ultrasonic energy on the time taken for a canned abalone to reach 80⁰C was tested. A thermocouple was inserted into the centre of a can of abalone and the can placed in a water bath maintained at 8O⁰C. The time taken to reach 8O⁰C was .measured (see Table 1). The test was repeated in a conventional ultrasonic cleaning bath, and with a conventional sonotrode at the settings indicated in Table.

In a further test highly propagating ultrasonic energy was applied to the water bath from a sonotrode placed in contact with the water 8O⁰C. The settings used are indicated in Table 1. The time taken to reach 8O⁰C was measured.

Table 1.0: Highly propagating ultrasonic energy increases heat transfer.

Time to heat the internal contents

Sonotrode type of canned abalone to 80°C

Conventional sonotrode for

30mins liquid immersion - 2OkHz at 400

Example 2: Enhanced heat transfer using highly propagating ultrasonic energy

Food and beverage products as listed in Table 2 were sealed in a 1 litre container (or can, or plastic bowl, or glass bottle) and immersed in a 40 litres of water at 7O⁰C. The time taken for the product at the centre of the container to reach 5O⁰C was measured using a thermocouple positioned inside the container. The experiment was then repeated with the application of highly propagating ultrasonic energy from a 1000 watt 2OkHz unit apparatus. The sonotrode of the apparatus was immersed in the water. The time taken for the product at the centre of the container to reach 5O⁰C after application of highly propagating ultrasonic energy was measured using a thermocouple positioned inside the container.

Table 2: Comparison of heat transfer times with and without application of highly ro a atin ultrasonic ener

These results illustrate that the application of highly propagating ultrasonic energy heat transfer is enhanced through the a container, can or bottle. Example 3: Application of highly propagating ultrasonic energy increases enhanced heat transfer in an evaporator.

The effect of the application of highly propagating ultrasonic on the flow rate required to evaporate a flow stream of skimmed milk powder, canola, palm oil to 57% solids from 35% solids was tested. The tests were performed in a flow through situation using a 18kHz transducer connected to an evaporator tube system. The heat energy generated by the steam in the evaporator is transferred through the steel tubing surface of the evaporator tube into the fluid stream.

In the absence of highly propagating ultrasonic energy the flow which allows evaporation to 57% solids from 35% solids is 8 gpm (approximately 30.3 litres per minute).

With the application of highly propagating ultrasonic energy at 18 kHz and 4,000 watts power the flow rate which allows evaporation to 57% solids from 35% solids is 11 gpm (approximately 41.6 litres per minute).

With the application of highly propagating ultrasonic energy at 18 kHz and 8,000 watts power the flow rate which allows evaporation to 57% solids from 35% solids is 14 gpm (approximately 53 litres per minute).

The effect of the application of highly propagating ultrasonic on the flow rate required to evaporate a flow stream of juice from sugar cane or sugar beet from 55% solids from 25% solids was tested. The tests were performed in a flow through situation using a 2OkHz transducer connected to an evaporator tube system. The heat energy generated by the steam in the evaporator is transferred through the steel tubing surface of the evaporator tube into the fluid stream.

In the absence of highly propagating ultrasonic energy the flow which allows evaporation to 55% solids from 25% solids is 3 gpm (approximately 11.3 litres per minute).

With the application of highly propagating ultrasonic energy at 20 kHz and 390 watts power, amplitude 4 microns the flow rate which allows evaporation to 55% solids from 25% solids is 5 gpm (approximately 20 litres per minute).

Example 4: Application of highly propagating ultrasonic energy decreases cooking time of rice. lOOg of rice was added to 50Og of water and the temperature maintained at 7O⁰C. hi the control reaction, the rice and water mixture was stirred and the time to cook the rice was measured as 21 minutes. The experiment was repeated with the application of highly propagating ultrasonic energy from a 2OkHz 400 watt laboratory device. When highly propagating ultrasonic energy was applied at 100 watts the cooking time of the rice was reduced to 14 minutes, when the highly propagating ultrasonic energy was applied at 300 watts the cooking time was 11 minutes and when the highly propagating ultrasonic energy was applied at 400 watts the cooking time was 6 minutes.

Example 5: Application of highly propagating ultrasonic energy decreases pasteurization time.

Orange juice was pasteurized at 75⁰C using a steam heated pasteurization tube in combination in the absence of ultrasound. The time taken for the orange juice to reach 75⁰C was measured. The time that the orange juice was maintained at 75⁰C to achieve a 5 log reduction in microorganism load was measured. The experiment was repeated with the application of highly propagating ultrasonic energy from a 2OkHz, 1000 watt ultrasound apparatus at power levels of 500 and 1000 watts. The ultrasound apparatus was connected to an external surface of the pasteurizer tube.

Table 4: Hi hl ro a atin ultrasonic ener decreases asteurization time

Example 6: Application of highly propagating ultrasonic energy decreases moisture content of spray dried milk and soya powder.

Skimmed milk was spray dried into powder with and without the application the application highly propagating ultrasonic energy. Highly propagating ultrasonic energy was applied using 17kHz, 4,000 watt ultrasound apparatus. The ultrasound apparatus was inserted into the -fluid medium as it flowed into a spray tower. As the viscosity of the fluid medium was reduced by 55%, the heat from the walls of the evaporator tower was transferred into the spray material at a faster rate resulting in a greater reduction in moisture content. The lower the moisture content in the spray dried product, the greater the heat transfer kinetics. After spray drying the moisture content of the milk powder was measured and compared with the moisture content of milk powder spray dried without that application of highly propagating ultrasonic energy .

Table 5: Highly propagating ultrasonic energy decrease moisture content of milk owder.

Table 6: Highly propagating ultrasonic energy decrease moisture content of soya rotein owder.

Tables 5 and 6 illustrate that the application of highly propagating ultrasonic energy reduces moisture content in the dried powder. This indicates that the ultrasonic energy enhances heat transfer into the product during spray drying compared to running the spray dryer without ultrasound.

Example 7: Application of highly propagating ultrasonic energy allows an increased flow rate without decreasing temperature rise.

An assembly for emitting highly propagating ultrasonic energy was clamped to a heat exchanger plate used to heat a flow stream containing corn/starch material to 38⁰C before delivery of the corn/starch material into a fermentation tank. The maximum flow rate attainable for the flow stream to reach 38⁰C was 80 GPM (approximately 364 litres/minute) without the application of highly propagating ultrasonic energy. When highly propagating ultrasonic energy was applied to the heat exchanger at 500 watts the maximum flow rate attainable for the flow stream to reach 38⁰C was 84 GPM (approximately 382 litres/minute). When highly propagating ultrasonic energy was applied to the heat exchanger at 1000 watts the maximum flow rate attainable for the flow stream to reach 38⁰C was 88 GPM (approximately 400 litres/minute). When highly propagating ultrasonic energy was applied to the heat exchanger at 1400 watts the maximum flow rate attainable for the flow stream to reach 38⁰C was 89 GPM (approximately 405 litres/minute). The application of highly propagating ultrasonic energy to the flow stream allows the flow rate to be increased while allowing the flow stream to attain the desired temperature.

Example 8: Application of highly propagating ultrasonic energy enhances thermal heat transfer into hydrocolloid based materials.

A mixture of water and gelatin (ratio 10:1) was heated to 6O⁰C and stirred. The time to gelatinization was measured. The test was repeated with the application of highly propagating ultrasonic energy at 500 or 900 watts from a 1000 watt 2OkHz probe to water and gelatin mixture at 6O⁰C. The time to gelatinization was measured.

Table 7: Hi hl ro a atin ultrasonic energy decrease gelatinization time of gelatin

A mixture of water and carrageenan (ratio 10:1) was heated to 9O⁰C and stirred. The time to gelatinization was measured. The test was repeated with the application of highly propagating ultrasonic energy at 500 or 900 watts from a 1000 watt 2OkHz probe to water and carrageenan mixture at 9O⁰C. The time to gelatinization was measured.

Table 8: Highly propagating ultrasonic energy decrease gelatinization time of cara eenan

A mixture of water and xanthaan gum (ratio 10:1) was heated to 8O⁰C and stirred. The time to gelatinization was measured. The test was repeated with the application of highly propagating ultrasonic energy at 500 or 900 watts from a 1000 watt 2OkHz probe to water and xanthaan gum mixture at 8O⁰C. The time to gelatinization was measured.

Table 9: Highly propagating ultrasonic energy decrease gelatinization time of xanthaan um

Example 9: Application of highly propagating ultrasonic energy enhances heat transfer into sliced potato slices during frying.

By way of a 10th example, ultrasound enhances the heat transfer into sliced potato slices during frying to make crisp snack foods 1 kg of sliced was fried in 501itres of either vegetable or Canola oil and the time to cook the potato to a desired level of browning and texture was measured. The test was repeated with the application of highly propagating ultrasonic energy to the oil using a 1000 watt 2OkHz apparatus.

Table 10: Hi hl ro a atin ultrasonic ener decreases r in time in ve etable oil

Example 10: Application of highly propagating ultrasonic energy enhances cooling rates.

The effect of highly propagating ultrasonic energy on the rate of cooling was tested. A thermocouple was placed in the centre of a 50Og and the temperature measured as 15⁰C. The chicken breast was immersed into a 1 litre ice bath at I⁰C. In the absence of ultrasound the chicken breast cooled I⁰C in 28 mins.

The experiment was repeated with the application of highly propagating ultrasonic energy at 2OkHz, 0.1 microns amplitude, 20 watts. With the application of highly propagating ultrasonic energy the chicken breast cooled from 15⁰C to I⁰C in 17 mins

A thermocouple was placed in the centre of a 500g bottle of orange juice and the temperature measured as 25⁰C. The bottle of orange juice was immersed into a 1 litre ice bath at I⁰C. In the absence of ultrasound the bottle of orange juice cooled I⁰C in 22 mins.

The experiment was repeated with the application of highly propagating ultrasonic energy at 2OkHz, 0.1 microns amplitude, 20 watts. With the application of highly propagating ultrasonic energy the bottle of orange juice cooled from 25⁰C to I⁰C m 11 mins

A thermocouple was placed in the centre of a 50Og bottle of tomato sauce and the temperature measured as 25⁰C. The bottle of tomato sauce was immersed into a 1 litre ice bath at I⁰C. In the absence of ultrasound the bottle of tomato sauce cooled I⁰C in 29 mins.

The experiment was repeated with the application of highly propagating ultrasonic energy at 2OkHz, 0.1 microns amplitude, 20 watts. With the application of highly propagating ultrasonic energy the bottle of tomato sauce cooled from 25⁰C to I⁰C in 15 mins

Example 11: Synergistic effect of highly propagating ultrasonic energy and pressure to reduce evaporation time of infant formula

The effect of the application of highly propagating ultrasonic energy with or without pressure on the flow rate required to evaporate a flow stream of infant formula to 55% solids from 31% solids was tested. The tests were performed in a flow through situation using a 2OkHz transducer connected to an evaporator tube system. The heat energy generated by the steam in the evaporator is transferred through the steel tubing surface of the evaporator tube into the fluid stream. The flow rate of the fluid stream was 5 gallons per minute (approximately 19 litres per minute). The power of the ultrasound was 480 watts power, amplitude 5 microns.

In the absence of highly propagating ultrasonic energy and at ambient pressure the flow which allows evaporation to 55% solids from 31% solids is 3 gpm (approximately 11.3 litres per minute).

In the absence of highly propagating ultrasonic energy but at a pressure of 1.5 bar, the flow rate which allows evaporation to 55% solids from 31% solids is 3.2 gpm (approximately 12.1 litres per minute).

With the application of highly propagating ultrasonic energy ultrasound the flow rate which allows evaporation to 55% solids from 31% solids is 4.4 gpm (approximately 16.7 litres per minute).

With the application of highly propagating ultrasonic energy ultrasound in combination with the application of pressure at 1.5 bar the flow rate which allows evaporation to 55% solids from 31% solids is 5.4 gpm (approximately 20.4 litres per minute).

With the application of highly propagating ultrasonic energy ultrasound in combination with the application of pressure at 3 bar the flow rate which allows evaporation to 55% solids from 31% solids is 6.8 gpm (approximately 25.7 litres per minute).

Claims

Claims:

1. A method for enhancing heat transfer into a solid comprising (i) applying heat to a mixture comprising a solid and a liquid

2. A method for enhancing heat transfer into a liquid comprising (i) applying heat to the liquid

3. The method of claim 1 or claim 2 further comprising the step of applying pressure to the solid or liquid wherein the pressure and highly propagating ultrasonic energy act synergistically to enhance the transfer of heat into said solid or liquid

4. A method for cooking a food comprising (i) applying heat to the food

5. The method of claim 4 further comprising the step of applying pressure to the food wherein the pressure and highly propagating ultrasonic energy act synergistically to transferring enhances heat transfer from the liquid into the food.

6. The method of claim 4 wherein the cooking apparatus is selected from the group consisting of a fryer, steamer, microwave oven, radio frequency oven electric or gas oven, retort cooker or boiling apparatus.

7. A method for pasteurisation of a solid or a liquid comprising (i) applying heat to the solid or liquid

8. The method of claim 7 further comprising the step of applying pressure to the solid or liquid wherein the pressure and highly propagating ultrasonic energy act synergistically to transfer heat into the solid or liquid.

9. The method of claim 7 or claim 8 wherein the heat transfer enhances reduction of microbiological load.

10. A method for producing a low moisture content spray dried powder from a liquid or slurry using a spray drying apparatus comprising

11. The method of claim 10 further comprising the step of applying pressure to the liquid or slurry wherein the pressure and highly propagating ultrasonic energy act synergistically to transfer heat into the liquid or slurry.

12. A method for cooling a solid or a first liquid comprising

13. The method of claim 12 wherein the first liquid is in a container.

14. The method of claim 12 or claim 13 further comprising the step of applying pressure to the solid or first liquid wherein the pressure and highly propagating ultrasonic energy act synergistically to transfer heat into the second liquid.

15. The method of any one of the preceding claims wherein the frequency of the highly propagating ultrasonic energy is the resonant frequency of the solid, liquid, slurry or food product.

16. The method of any one of the preceding claims wherein the frequency of the highly propagating ultrasonic energy is about 16 kHz to about 20 kHz.

17. The method of any one of the preceding claims wherein the amplitude of the highly propagating ultrasonic energy is about 0.001 -micron to about 500 microns.

18. The method of any one of the preceding claims wherein the amplitude of the highly propagating ultrasonic energy is about 0.01-micron to about 20 microns.

19. The method of any one of the preceding claims wherein the highly propagating ultrasonic energy is applied at an energy density of between about 0.00001 watt/cm³ to about 1000 watt/cm³.

20. The method of any one of the preceding claims wherein the highly propagating ultrasonic energy is applied at an energy density of between about 0.0001 watt/cm³ to about 50 watt/cm³.

21. The method of any one of the preceding claims wherein the highly propagating ultrasonic energy is applied at a frequency between about 16 KHz and about 20 KHz and at an amplitude of between 0.001 -micron to about 500 microns and at an energy density of between about 0.0001 watt/cm³ to about 100 watts/cm³.

22. The method of any one of the preceding claims wherein the highly propagating ultrasonic energy is applied at an energy density of between about 16 KHz and about 20 KHz and at an amplitude of between 0.01-micron to about 20 microns and at an energy density of about 0.0001 watt/cm³ to about 50 watt/cm³.

23. A method of enhancing heat transfer through a solid surface of a container and into a solid or liquid inside the container, the method comprises

(i) applying heat to the surface

(ii) contacting the surface with a high power transducer or sonotrode (iii) applying highly propagating ultrasonic energy from the transducer or sonotrode across the surface wherein the transducer or sonotrode vibrates at a frequency of between about 16 KHz and about 500 KHz and wherein the highly propagating ultrasonic energy enhances heat transfer across and through the surface and into the solid or liquid or materials inside the surfaces or boundaries.

24. The method of claim 23 wherein the sonotrode is immersed in a coupling liquid wherein the coupling liquid is in contact with the container.

25. The method of claim 24 wherein the solid or liquid inside the container is a flow stream.

26. The method of claim 23 wherein the transducer includes a vibration direction conversion member.

27. The method of claim 23 wherein the frequency of the highly propagating ultrasonic energy is between about 16 KHz and about 40 BCHz.

28. The method of claim 20 wherein the frequency of the highly propagating ultrasonic energy is between about about 16 KHz and about about 20 KHz

29. The method of claim 23 wherein the temperature of the solid or liquid is raised to between about 20°C and about 500°C.

30. A method for enhancing heat transfer into a solid comprising (i) applying heat to a mixture comprising a solid and a liquid

31. A method for enhancing heat transfer into a liquid comprising (i) applying heat to the liquid

32. A method for cooking a food comprising (i) applying heat to the food

(iϊ) applying highly propagating ultrasonic energy to the food wherein the highly propagating ultrasonic energy is uniformly distributed throughout said food thereby enhancing the transfer of the heat into said food.

33. A method for pasteurisation of a solid or a liquid comprising (i) applying heat to the solid or liquid

34. A method for producing a low moisture content spray dried powder from a liquid or slurry using a spray drying apparatus comprising

(i) contacting at least a portion of said spray drying apparatus with a highly propagating ultrasonic energy emitting assembly; and (ii) operating the spray drying apparatus wherein the liquid or slurry is vapourised and;

(iii) applying highly propagating ultrasonic energy wherein the highly propagating ultrasonic energy is uniformly distributed throughout the vapourised liquid or slurry and wherein the highly propagating ultrasonic energy enhances heat transfer into the liquid or slurry thereby decreasing the moisture content of the spray dried powder.

35. A method for cooling a solid or a first liquid comprising

36. The method of any one claims 30 to 35 wherein the frequency of the highly propagating ultrasonic energy is between about 10 KHz and about 2000 KHz or between about 10 KHz and about 1500 KHz, or between about 10 KHz and about 1000 KHz, or between about 10 KHz and about 750 KHz₅ or between about 10 KHz and about 400 KHz, or between about 10 KHz and about 250 KHz, or between about 10 KHz and about 125 KHz, or between about 10 KHz and about 100 KHz, or between about 10 KHz and about 60 KHz, or between about 10 KHz and about 40 KHz, or between about 10 KHz and about 30 KHz, or between about 10 KHz and about 20 KHz, or between about 16 KHz and about 40 KHz, or between about 10 KHz and about 30 KHz, or between about 16 kHz and about 26kHz or between about 19 KHz and about 28 KHz, or between about 16 KHz and about 22 KHz, or between about 16 KHz and about 20.0KHz.