RU2499198C1 - Control method of hot water supply temperature mode, and device for its implementation - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: method and device for control of hot water supply temperature mode are proposed. The proposed method consists in measurement of hot water temperature T_H and its maintenance at the specified level of hot water temperature T_HS. In order to obtain hot water, water from return line with volume V_R is mixed in a mixing chamber with volume V_MC with water from supply line with volume V_S in the ratio of V_R/V_S=(T_S-T_R)/(T_S-T_H)-1, where V_R+V_S=V_MC. Before water is supplied from the supply line to the mixing chamber, current value of hot water volumetric flow rate V_H is fixed as initial value V_H(REF). Water is supplied from the supply line with volume V_S to the mixing chamber in the form of a pulse till condition V_H-V_H(REF)=V_S is met; after that, water supply from the supply line with volume V_S to the mixing chamber is stopped and water from the return line with volume V_R is supplied to the mixing chamber. A device implementing the above method includes a supply line, a switch, a mixing chamber, a water temperature measuring device, a return line, a check valve and a flow metre.

EFFECT: improvement of a method.

2 cl, 1 dwg

Description

The invention relates to heat engineering and can be used to control hot water supply of residential and administrative buildings and structures.

A known method of automatic control of a hot water supply system (RF Patent No. 2273800, F24D 17/00, 2004), which includes measuring the temperature of hot water T _g and maintaining it at a given level of hot water temperature T _{gz by} changing the flow rate of heating water in the heat exchanger.

The disadvantage of this method is the high energy intensity and cost, as well as the significant complexity of the implementation, due to the use of a heat exchanger and a special control valve with a drive and the need for heating cold water.

Closest to the claimed is the "Method of controlling a hot water supply system" (USSR Author's Certificate No. 1495583, F24D 17/00, 1987), adopted as a prototype, which consists in measuring the temperature of hot water T _g and maintaining it at a given level of hot water temperature T _{gz by} changing the flow rate of heating water in the heat exchanger, as well as in measuring the temperature of the water in the return pipe T _about before and after the first stage of the water heater.

The disadvantage of this method is the significant complexity of the implementation, which is associated with the need to use two heat exchangers. In addition, the use of a circulation pump and a special control valve with a drive increases the energy consumption and reduces the reliability of the implementation of this method of regulating hot water supply, and the thermal inertia of the heat exchangers adversely affects the speed of the process of regulating the water temperature.

The technical result of the proposed method is to ensure the speed, reliability and economy of temperature control of hot water supply.

The technical result is achieved by the fact that in the method of regulating the temperature of hot water supply, which consists in measuring the temperature of hot water T _g and maintaining it at a given level of hot water temperature T _gz , as well as in measuring the temperature of the water in the return pipe T _o , measure the water temperature in the supply line T _p and the volumetric flow rate of hot water V _g , and to obtain hot water, mix water from the return line of volume V _о with water from the supply line of volume V in a mixing chamber of volume V _ck m V _p in proportion

V _o / V _p = (T _p -T _o ) / (T _rz -T _g ) -1,

V _about + V _p = V _SC .

Before supplying water from the supply line to the mixing chamber, the current value of the volumetric flow rate of hot water V _{g is} recorded, as the original V _{g (out} ), water is supplied from the supply line of volume V _p to the mixing chamber in the form of a pulse until the condition

V _g -V _{g (original} ) = V _p ,

after which the water supply from the supply line of volume V _p to the mixing chamber is stopped and water is supplied to the mixing chamber from the return line of volume V _about , and when the condition

V _g -V _{g (original} ) = V _ck

complete the current cycle of regulating the temperature of hot water T _g and carry out the next cycle of regulating the temperature of hot water T _g

Adjusting the proportion to be mixed in a mixing water chamber from the return flow volume V _of the water from the flow line volume V _n if the hot water temperature deviation T _g of the target hot water temperature level T _rs exceeds the permissible value δ of error control of hot water temperature T _r

| T _r -T _rz |> δ.

A device for controlling the temperature regime of hot water supply contains a supply line connected through a water temperature meter in the supply line and a key to the first input of the mixing chamber, a return line is connected to the second input of which through a water temperature meter in the return line and a check valve, and the output of the mixing chamber is connected through hot water temperature meter and flow meter connected to the inlet of the hot water consumer. The second output of the water temperature meter in the supply line is connected to the first input of the control unit, to the second input of which the hot water temperature setting unit is connected, the second output of the flow meter is connected to the third input of the control unit, the fourth input of the control unit is connected to the second output of the hot water temperature meter, fifth the input of the control unit is connected to the second output of the water temperature meter in the return line, and the output of the control unit is connected to the second input of the key.

The drawing shows a block diagram of a device that implements the proposed method for regulating the temperature regime of hot water supply.

The device contains a supply line 1 connected through a water temperature meter in the supply line 2 and a key 3 to the first input of the mixing chamber 4, to the second input of which a return line 7 is connected through a water temperature meter in the return line 5 and a check valve 6, and the output of the mixing chamber 4 through a hot water temperature meter 8 and a flow meter 9 is connected to the input of the hot water consumer 10. The second output of the water temperature meter in the supply line 2 is connected to the first input of the control unit 11, in the other input of which the hot water temperature setting unit 12 is connected, the second output of the flowmeter 9 is connected to the third input of the control unit 11, the fourth input of the control unit 11 is connected to the second output of the hot water temperature meter 8, the fifth input of the control unit 11 is connected to the second output of the water temperature meter in the return line 5, and the output of the control unit 11 is connected to the second input of the key 3.

If the temperature of hot water T _g differs from a predetermined level of hot water temperature T _gz , for example, T _g <T _gz , then to ensure that the condition T _g = T _{gz is} fulfilled, the increment of thermal energy ΔQ _g in the mixing chamber 4 with a volume of V _c

$$\Delta Q_g=c\cdot g\cdot V_{\mathrm{from}\mathrm{to}}\cdot \left(T_{gs}-T_g\right),\left(\text{one}\right)$$

where c is the specific heat of water, J / (kg · ° C);

g is the density of water, kg / m ³ .

On the other hand, the increment of thermal energy ΔQ _{g is} provided by mixing water from the return line 7 with a volume of V _о and a temperature Т _о with water from a supply line 1 with a volume of V _p and a temperature T _p

$$\Delta Q_g=c\cdot g\cdot V_P\cdot \left(T_P-T_{\mathrm{about}}\right).\left(\text{2}\right)$$

Given that

$$V_{\mathrm{about}}+V_P=V_{\mathrm{from}\mathrm{to}},\left(\text{3}\right)$$

we obtain from formulas (1) and (2)

$$V_{\mathrm{about}}=V_{\mathrm{from}\mathrm{to}}\cdot \left(\mathrm{one}-\left(T_{gs}-T_g\right)/\left(T_P-T_{\mathrm{about}}\right)\right),\left(\text{four}\right)$$

$$V_P=V_{\mathrm{from}\mathrm{to}}\cdot \left(T_{gs}-T_g\right)/\left(T_P-T_{\mathrm{about}}\right),\left(\text{5}\right)$$

$$V_{\mathrm{about}}/V_P=\left(T_P-T_{\mathrm{about}}\right)/\left(T_{gs}-T_g\right)-\mathrm{one.}\left(\text{6}\right)$$

Mixing water from the return line 7 with a volume of V ₀ and temperature T _о with water from the supply line 1 with a volume of V _p and a temperature T _p in the mixing chamber 4 in proportion (6), taking into account relation (3), satisfies the condition T _g = T _gz .

Implementing the method, the device operates as follows.

In the initial state, the key 3, for which, for example, a shut-off solenoid valve can be used, is closed, and water from the return line 7 through the water temperature meter in the return line 5, the check valve 6, the mixing chamber 4, the hot water temperature meter 8, the flow meter 9 is supplied to the hot water consumer 10. The hot water temperature setting unit 12 sets the value of the hot water temperature T _gz . The water temperature meter in the supply line 2 provides continuous monitoring of the water temperature T _p in the supply line 1, and the water temperature meter in the return line 5 provides continuous monitoring of the water temperature T _about in the return line 7.

Since in the initial state the hot water temperature measured by the hot water temperature meter 8 is T _g = T _o <T _gz , the control unit 11 calculates by formula (5) the required volume V _{p of} supply from the supply line 1 to the mixing chamber 4, fixes the current value of the volumetric flow rate hot water V _g , measured by the flow meter 9, as the original V _{g (out)} , and opens the key 3. However, due to the difference in water pressure in the supply line 1 and in the return line 7, the water from the return line 7 to the mixing chamber 4 is not arrives, and the presence of the inverse to Apaana 6 eliminates the ingress of water from the supply line 1 and a return line 7.

A water pulse with a temperature T _p from the supply line 1 is fed into the mixing chamber 4, where it is mixed with water with a temperature T ₀ from the return line 7 until the condition

$$V_g-V_{g\left(\mathrm{and}\mathrm{from}x.\right)}=V_P,\left(\text{7}\right)$$

after which the key 3 is closed and water enters the mixing chamber 4 with a temperature T ₀ from the return line 7.

When the condition is met

$$V_g-V_{g\left(\mathrm{and}\mathrm{from}x.\right)}=V_{\mathrm{from}\mathrm{to}}\left(\text{8}\right)$$

the current cycle of regulating the temperature of hot water T _{g is completed} and the next cycle of regulating the temperature of hot water T _{g is} carried out _by fixing the current value of the volumetric flow rate of hot water V _g , as the original V _{g (} original ₎ , and opening the key 3.

The correction of the proportion (6) of water mixed in the mixing chamber from the return line of volume V _о and temperature Т _о with water from the supply line of volume V _p and temperature T _{p is} performed by the control unit 11 only when the temperature of hot water T _g deviates from the set level of hot water temperature T _rs for a predetermined in the control unit 11, the error permissible value δ hot water temperature control T _r

$$\left|T_g-T_{gs}\right|>\delta .\left(\text{9}\right)$$

In the absence of hot water consumption, i.e. if there is no change in the volumetric flow rate of hot water V _g , the control unit 11 closes the key 3, and the process of regulating the temperature of hot water T _g stops.

Thus, given the high working resources and low energy consumption of the electromagnetic valve and the control unit, as well as the absence of devices with significant thermal inertia, the implementation of the proposed method allows for high speed, reliability and cost-effectiveness of temperature control of hot water supply.

Claims (2)

1. The method of regulating the temperature of hot water supply, which consists in measuring the temperature of hot water T _g and maintaining it at a predetermined level of hot water temperature T _gz , as well as in measuring the temperature of the water in the return pipe T _o , characterized in that they measure the temperature of the water in the supply the mains T _p and the volumetric flow rate of hot water V _g , and in order to obtain hot water, water from the return main of volume V _o and water from the supply main of volume V _p are mixed in a mixing chamber of volume V _c in proportion
V _o / V _p = (T _p -T _o ) / (T _gz- T _g ) -1, V _o + V _p = V _ck , while the current value of the hot volumetric flow rate is recorded before the water from the supply line to the mixing chamber water V _g , as the original V _{g (} original ₎ , feed water from the supply line of volume V _p into the mixing chamber in the form of a pulse until the condition
V _g -V _{g (original)} = V _p ,
after which the water supply from the supply line of volume V _p to the mixing chamber is stopped and water is supplied to the mixing chamber from the return line of volume V _o , and when the condition
V _g -V _{g (original)} = V _c complete the current cycle of regulating the temperature of hot water T _g and carry out the next cycle of regulating the temperature of hot water T _g , and adjust the proportion of water mixed in the mixing chamber from the return line of volume V _o with water from the supply mains with a volume of V _p in the event that the deviation of the hot water temperature T _g from the set level of the hot water temperature T _gz exceeds the permissible value δ of the error in regulating the temperature of hot water T _g | T _g -T _gz |> δ. 2. A device for controlling the temperature of hot water supply, characterized in that it contains a supply line connected through a water temperature meter in the supply line and a key to the first input of the mixing chamber, to the second input of which a check valve is connected through a water temperature meter in the return line and a check valve the line, and the output of the mixing chamber through the hot water temperature meter and flow meter is connected to the inlet of the hot water consumer, the second output of the tempera meter The water in the supply line is connected to the first input of the control unit, to the second input of which the hot water temperature setting unit is connected, the second output of the flow meter is connected to the third input of the control unit, the fourth input of the control unit is connected to the second output of the hot water temperature meter, the fifth input of the control unit connected to the second output of the water temperature meter in the return line, and the output of the control unit is connected to the second input of the key.