DE3331825A1 - CHEMICAL HEAT PUMP WITH LONG-TERM CHEMICAL STORAGE - Google Patents

Description

333Ί825

description

The invention relates to a chemical heat pump that uses heat, i.e. powered by thermal energy, for pumping anergy from a room of reference temperature to a room of higher "temperature" according to the preamble of claim 1.

The heat pump should absorb heat for the drive, solar heat in summer or in periods of high waste heat supply from other sources, and pumping anergy into a room with a higher than the reference or Ambient temperature for heating the same in winter or in Get periods of insufficient heat supply. She is for that purpose Equipped with a memory that absorbs the exergy of the drive heat flow in the form of chemical energy and contributes to pumping anergy Needs again. The energy balance is broken down as follows, where losses are neglected for easier understanding (E = exergy, A = anergy):

- For the drive of the heat pump, that means according to the generic term of claim 1, for the endergonic forward reaction or desorption applies:

Drive energy, thermal

(entered) 2 I + O

Waste heat

(output) - (I + O)

- So it remains:

stored exergy E

- For pumping the heat pump, which means according to the preamble of claim 1, for the exergonic reverse reaction or absorption
is applicable :

Anergy

(entered) A.

Exergy

(entered) E.

Heating

(output) - (E + O)

If the annual consumption figure ψ is formed, it is defined as the ratio of exergy supplied to the total thermal energy given off

this corresponds to the Carnot factor of the heating task averaged over the heating period. The relationship also applies if the annual consumption figure φ is the ratio of stored exergy E to heat generated by pumping (E + A). <f> has values around 0.07 for a location of the heat pump in the climatic region of Central Europe; Because of the unavoidable loss of exergy, actually achievable values for the annual consumption figure are between 0.25 and 0.7.

The state of the art for heat pumps with storage is indicated through zeolite storage heat pumps. Zeolites are solids that can absorb water vapor while releasing energy. Zeolites can thus find use as a sorbent when water is used as a refrigerant; it is absorption and desorption of the two Reaction partner in the strict sense not a chemical reaction but rather a physical adsorption process. The zeolite heat pumps are nevertheless mentioned, since chemical heat pumps with chemical Memory has not yet been written to. (Chemical heat pumps without a storage tank are not entirely applicable as absorption heat pumps because desorption processes also take place in them. In conventional heat pumps, the refrigerant is not water but, for example, NH3; they are therefore different in comparison to the invention the end.)

Zeolite storage heat pumps cause a number of fundamental problems with it due to the fact that the sorbent is a solid. The heat transfer to those saturated with water Zeolite, for example via heat exchangers, requires a large number of surfaces and reliable contact with the solid; because Due to the low partial pressure of the refrigerant water, the entire desorption process must take place in a fine vacuum. Since the zeolite is only available in Boundaries is pourable, the distinction between desorber and Storage (as well as the one between absorber and storage) obsolete: The store itself with the zeolite supply is both an absorber and a also desorber. This results in a periodic mode of operation - what is responsible - but also the heating of the entire zeolite stock, or, if this is avoided by dividing the heat exchanger

SUBSCRIBED

den is a complex circuit of the same. If you want air as a heat transfer medium and at the same time as a means of transporting water vapor internal heat exchangers and fine vacuum can be dispensed with; the problems are now due to the high flow resistance due to the bed, which requires a great deal of exergy for the fan.

The invention is based on the task of storing the exergy the thermal drive energy for the heat pump over a longer period of time, sufficient for one season, chemically inexpensive, to enable reliable with minimal technical effort and minimal exergy requirement for auxiliary units, whereby it should be pointed out is that desorption and absorption know here, if necessary, also run in parallel with different power.

This task is achieved in a generic device by the Features of claim 1 solved.

The advantage of solving this problem is when used as a sorbent an easy and inexpensive to store liquid with extremely low vapor pressure at ambient temperature and as a refrigerant Water is used, for example air as a heat transfer medium and water vapor transport medium for both desorption and for the absorption can come into question, with the free enthalpy of reaction in the reaction of sorbent and refrigerant should be high. However, this is not necessary, especially with aggressive sorbents such as sulfuric acid, direct contact with the heat exchanger, because For example, the drive heat is supplied to the air, the shark heat to the Air is taken. In particular, the desorption can be carried out at a relatively low temperature at ambient pressure, since the The partial pressure of the water vapor load is now almost independent of the absolute pressure in the desorber.

Two exemplary embodiments of the invention are shown in FIGS. 1 and 2.

Figure 1 shows a closed circuit with storage tanks for sorbent, refrigerant water and reaction product.

Figure 2 shows a half-open circuit with regard to the refrigerant with storage tanks only for the sorbent and the reaction product of sorbent and refrigerant water.

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Claims (1)

Chemical heat pump with
chemical long-term storage Claims Chemical heat pump for pumping anergy A from one
Room from reference temperature to a room of higher temperature based on the one hand on a reversible chemical reaction between a refrigerant and a sorbent as
Reaction partner, divided into an endergonic forward reaction to separate the two reactants from their common reaction product, known as desorption, and an exergonic one
Reverse reaction to unite the two reactants in
their common reaction product, called absorption, based on the other hand on a reversible thermodynamic phase change liquid - gaseous for the refrigerant in form of evaporation and condensation, consisting on the one hand of a first thermochemical reactor for the forward reaction, composed of desorber and condenser, on the other hand consisting of a second thermochemical reactor for the reverse reaction, composed of evaporator and absorber, interconnected in a common circuit with circulation pumps to absorb thermal energy (2E + A) to drive the heat pump, composed of exergy E and anergy A, for
Carrying out the forward reaction in the first reactor, that is, for desorption in the desorber with simultaneous evaporation of the refrigerant with subsequent liquefaction of the separated " ² " COPY] Refrigerant in the condenser giving off thermal Energy (E + A) to the room with a higher temperature, and for the release of thermal energy (E + A), composed of the exergy E and transferred by the reactants from anergy A, recorded from the room at reference temperature through evaporation of the refrigerant in the evaporator, in the reverse reaction, characterized in that between the first reactor, consisting consisting of a desorber and a condenser, and a second reactor, consisting of an evaporator and absorber, each with a tank for holding liquid Refrigerant, liquid sorbent and liquid reaction product for storing exergy in the form of chemical energy are switched on, so that the feed of the drive energy into the heat pump and the release of the stored energy to absorb the anergy from the environment can be shifted against each other over any period of time can, according to claim 1, characterized in that when water is used as the refrigerant, the associated tank can be dispensed with, wherein the liquefied refrigerant is released into the environment and the water required for the reverse reaction is removed from the environment will, according to claim 1 and 2, characterized in that a large number of sorbents and reaction products are common Subunits divided tank is provided, with emptying and filling of the subunits alternating in time takes place with sorbent and reaction product.