JP2005265329A - Heat collecting method from air-conditioning exhaust air and system therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To preclude cross-contamination, assure a high collecting efficiency from the air-conditioning exhaust air, and perform heat collection from the air-conditioning exhaust air even if the temperature difference between the air-conditioning exhaust air and the outside air lessens. <P>SOLUTION: Heat exchange between the air-conditioning exhaust air EA and water by gas-liquid contacting inside a filler 14 is conducted in an air-conditioner 10. A temperature sensor 25 is installed on a forward pipe 23 leading from a receptacle part 13 to a pre-coil 22 in a duct 21, and a control device 27 controls an inverter 26 so that the temperature signal from the sensor 25 generates the set temperature predetermined, and a flow control is conducted using a pump 24 to control the temperature of the water as a heating medium circulating. The set temperature is corrected according to the temperature of the outside air. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method and system for recovering heat from air conditioning exhaust.

  Conventionally, exhaust heat in air conditioning has been recovered and reused as a heat source for air supply. In such a case, for example, a rotary heat storage rotor is used to exchange heat between the exhaust and the supply air via the rotor. Although this method can recover both sensible heat and latent heat, it has the advantage of high recovery efficiency. However, since the supply air and the exhaust are in direct contact with each other through the rotor, harmful or uncomfortable components contained in the exhaust are eliminated. There was a problem that a phenomenon (cross-contamination) mixed with air supply occurred.

  On the other hand, by installing a coil in each of the exhaust duct and the air supply duct and circulating a heat medium between the two coils, the heat on the exhaust side is recovered, and this is recovered again by the heat medium via the coil on the air supply side. There is also a method of exchanging heat and reusing it as a heat source for supply air. However, although this method can prevent cross-contamination, there is a problem that latent heat cannot be recovered and recovery efficiency is low.

  Furthermore, heat exchange is performed between the air-conditioning exhaust and a liquid heat medium such as water through a filling sprinkled with the liquid heat medium, and the liquid heat medium after heat exchange is recovered and stored in a heat storage tank. It has been proposed to use it as a heat source for air conditioning such as a heat pump (Patent Document 1).

  By the way, when heat exchange between the air-conditioning exhaust and the liquid heat medium such as water is performed by gas-liquid contact, the temperature of the air-conditioning exhaust is usually constant. For example, if the temperature of the outside air decreases, the air-conditioning exhaust and the outside air The energy difference required for heat recovery operation may be larger than the amount of heat recovered.

JP-A-56-113965

  The present invention has been made in view of the above points, and can prevent cross-contamination, has high recovery efficiency from air-conditioning exhaust, and can recover heat even if the temperature difference between the air-conditioning exhaust and outside air becomes small. The aim is to provide a method and system that can be continued.

  In order to achieve the above object, the heat recovery method of the present invention performs heat exchange by directly contacting a liquid heat medium and air-conditioning exhaust in a heat exchanger capable of gas-liquid contact in a container, and the liquid heat medium is a coil. Is circulated between the heat exchanger and the heat exchanger, heat is exchanged between the liquid heat medium and the intake outside air via the coil, and the amount of circulation is adjusted so that the temperature of the liquid heat medium becomes a set temperature. It is characterized by control.

  When the temperature of the air-conditioning exhaust is constant, heat recovery can be sufficiently performed by reducing the circulation amount of the liquid heat medium circulated between the coil and the heat exchanger. For example, in the summer, the temperature of the liquid heat medium can be lowered and the heat recovery can be continued by reducing the amount of the liquid heat medium when reducing the amount of circulation and bringing it into gas-liquid contact with the air conditioning exhaust. That is, as in the present invention, heat recovery from the air-conditioning exhaust can be continued by controlling the circulation amount so that the temperature of the liquid heat medium becomes the set temperature.

  The set temperature is determined based on the temperature of the outside air. For example, in the cooling operation, when the outside air temperature is 25 ° C., the set temperature is 17.5 ° C., and when the outside air temperature is 35 ° C., the set temperature is 20 ° C. It can be proposed that the wet bulb temperature of the exhaust be set as the set temperature between 0 ° C and in heating operation.

  As a system for carrying out such a method, a heat exchanger capable of gas-liquid contact in a container and exchanging heat between gas and liquid, a water spraying unit for spraying a liquid heat medium toward the container, A receiving part for receiving the sprinkled liquid heat medium, a coil installed in the flow path of the intake outside air, a forward path of the liquid heat medium formed between the receiving part and the coil, the coil and the A liquid heat medium return path formed between the water sprinkling unit, a pump provided in the forward path or return path, a flow controller provided in the forward path or return path, and provided in the forward path or return path A temperature sensor that measures the temperature of the liquid heat medium, and a control device that controls the flow rate regulator so that the temperature of the liquid heat medium measured by the temperature sensor becomes a preset temperature. A system can be proposed.

  As the heat exchanger, for example, a cooling tower such as a cooling tower having a sprinkler installed above an open container and a receiving part for receiving the sprinkled liquid heat medium below the container can be exemplified. Sprinkling may be performed directly on the air-conditioning exhaust, but if the water is sprinkled on the filling and heat exchange is performed by contacting the air-conditioning exhaust via this filling, the gas-liquid contact efficiency is improved. In addition, the heat exchange rate is improved. As the liquid heat medium, for example, water can be used.

  According to the present invention, since the circulation amount of the liquid heat medium is controlled based on the temperature of the liquid heat medium, the circulation amount is adjusted according to the temperature of the outside air, and the heat from the air conditioning exhaust is recovered. Can continue.

  Hereinafter, preferred embodiments of the present invention will be described. As shown in FIG. 1, the heat exchanger 10 has a watering part 12 in a container 11 whose upper part is open like a cooling tower, and a lower part in the container 11 constitutes a receiving part 13. Yes. A filler 14 is disposed below the sprinkler 12.

  The air-conditioning exhaust EA from the load side is introduced below the filling 14 in the container 11 through an exhaust duct 15 connected to the side surface of the container 11.

  On the other hand, the supply air SA is configured to be supplied to an air conditioner (not shown) from the duct 21 for introducing the intake outside air OA. In the present embodiment, a precoil 22 is disposed in the duct 21. The precoil 22 functions as a precooler in summer and functions as a preheater in winter.

  Between the inlet side of the precoil 22 and the receiving part 13 of the heat exchanger 10, for example, an outgoing pipe 23 for circulating water as a liquid heat medium is provided. The outgoing pipe 23 is provided with a pump 24. The outgoing pipe 23 is provided with a temperature sensor 25 for measuring the temperature of the liquid heat medium flowing in the outgoing pipe 23. The pump 24 is controlled by an inverter 26, whereby the flow rate of the liquid heat medium flowing in the outgoing pipe 23 is adjusted. By controlling the inverter 26, for example, as shown in FIG. 2, the outlet temperature of the heat exchanger 10 for the liquid heat medium (water), that is, the temperature of the liquid heat medium (water) flowing through the outgoing pipe 23 can be controlled. it can.

  The temperature signal from the temperature sensor 25 is input to the control device 27. The control device 27 compares the set temperature set in advance with the measured temperature from the temperature sensor 25 and controls the frequency of the inverter 26 so that the temperature of the liquid heat medium flowing through the outgoing pipe 23 becomes the set temperature. Thus, the flow rate of the liquid heat medium flowing through the outgoing pipe 23 is controlled.

  The set temperature in the control device 27 is determined based on the temperature of the outside air. The outside air is output to the control device 27 by the temperature sensor 28. The control device 27 sets the temperature of the outside air at −15 ° C. to 7.5 ° C., for example, as shown in FIG. 3 based on a program designated in advance. The temperature is automatically set.

  A return pipe 29 is piped between the outlet side of the pre-coil 22 and the water sprinkling part 12 of the heat exchanger 10. Then, the liquid heat medium from the return pipe 29 is sprinkled from the sprinkler 12 to the filler 14. In this way, the liquid heat medium circulates between the pre-coil 22 and the heat exchanger 10 via the forward pipe 23 and the return pipe 29.

The heat recovery system according to the present embodiment is configured as described above, and the following operation example will be described.
(Example during summer cooling operation)
For example, the air volume of the air conditioning exhaust EA is 34500 m ³ / h, the dry bulb temperature is 23 ° C., the relative humidity is 50%, and the unit heat amount is 10.83 Kcal / kg.
When the air volume of the incoming outside air OA is 42000 m ³ / h, the dry bulb temperature is 35 ° C., the relative humidity is 60%, and the unit heat quantity is 21.53 Kcal / kg,
When water is used as the liquid heat medium,
When the amount of water is 882 l / min,
The temperature of the water flowing in the outgoing pipe 23 is 20.1 ° C.
The temperature of the water flowing in the return pipe 29 is 22.9 ° C.
The supply bulb SA had a dry bulb temperature of 26.0 ° C., a relative humidity of 95%, and a unit calorie of 18.56 Kcal / kg.

Therefore, the recovered heat amount in this case is 1.2 × 42000 × (21.53-18.56) = 149688 kcal / h,
The recovery efficiency is (21.53-18.56) / (21.53-10.83) = 27.8%.
The power consumption when the recovered heat is not recovered is 149688 kcal / h ÷ 860 kcal / kW ÷ 5.0 = 34.8 kW, assuming that the coefficient of performance is 0.5. The power consumed for heat recovery is 2.9 kW, and the difference of 31.9 kW can be reduced.

(Example during winter heating operation)
For example, the air volume of the air conditioning exhaust EA is 34500 m ³ / h, the dry bulb temperature is 23 ° C., the relative humidity is 50%, and the unit heat amount is 10.83 Kcal / kg.
When the air volume of the incoming outside air OA is 42000 m ³ / h, the dry bulb temperature is 5 ° C., the relative humidity is 60%, and the unit heat quantity is 3.13 Kcal / kg,
When water is used as the liquid heat medium,
When the amount of water is 780 l / min,
The temperature of the water flowing in the outgoing pipe 23 is 16.2 ° C.
The temperature of the water flowing in the return pipe 29 is 14.4 ° C.
The supply bulb SA had a dry bulb temperature of 11.9 ° C., a relative humidity of 38.0%, and a unit calorie of 4.82 Kcal / kg.
Therefore, in this case, the recovered heat amount is 85176 kcal / h, and the recovery efficiency is 21.9%.

  Compared with the conventional method of recovering the heat of the air conditioning exhaust EA by installing coils in the air conditioning exhaust duct and the air supply duct and circulating water between the two coils, the conventional method has 7 .4% and 8.2% in winter. Therefore, it can be seen that the recovery efficiency of the present invention is much improved in both summer and winter compared to the conventional method.

  Further, in the present embodiment, the temperature sensor 23 sequentially monitors the temperature of the liquid heat medium flowing in the outgoing pipe 23, and the control device 27 controls the inverter 26 so that the temperature becomes a preset temperature. Since the set temperature in the device 27 is determined based on the temperature of the outside air measured by the temperature sensor 28, for example, when the temperature of the outside air rises, the set temperature is raised accordingly, and the set temperature The inverter 26 is controlled so that the temperature of the liquid heat medium flowing in the outgoing pipe 23 is controlled, and the heat recovery from the air-conditioning exhaust EA can be recovered within a certain range. Therefore, even if the temperature of the outside air rises or falls, it is possible to always recover heat within a certain range.

  Of course, since the air-conditioning exhaust EA and the supply air SA are not in direct contact with each other, cross contamination is also prevented.

In the above embodiment, the pump 24, the inverter 26, and the temperature sensor 25 are provided on the outgoing pipe 23 side, but may be provided on the return pipe 29 side.
In the above embodiment, the flow regulator is the inverter 26 provided in the pump. However, instead of this, as shown in FIG. Good. In this case, the control device 27 compares the set temperature set in advance with the measured temperature from the temperature sensor 25 and adjusts the flow rate so that the temperature of the liquid heat medium flowing in the outgoing pipe 23 becomes the set temperature. What is necessary is just to control the flow volume of the liquid heat medium which flows through the outgoing pipe 23 by controlling the opening degree of the valve 31.

It is explanatory drawing which shows the structural example of the heat recovery system concerning this Embodiment. It is a graph which shows the relationship between the circulation amount of a liquid heat medium, and the heat exchanger exit side temperature of a liquid heat medium. It is a graph which shows the example of control of preset temperature based on outside temperature. It is explanatory drawing which shows the structural example of the heat recovery system concerning other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Heat exchanger 12 Sprinkling part 13 Receiving part 22 Precoil 23 Outgoing pipe 25 Temperature sensor 26 Inverter 27 Control apparatus 29 Return pipe EA Air-conditioning exhaust OA Intake external air SA Supply air

Claims (3)

A method for recovering and reusing heat from air-conditioning exhaust, wherein the liquid heat medium and air-conditioning exhaust are brought into direct contact with each other in a heat exchanger capable of gas-liquid contact in the container to exchange heat, and the liquid The heat medium is circulated between the coil and the heat exchanger, and heat exchange is performed between the liquid heat medium and the intake outside air via the coil.
A method for recovering heat from air-conditioning exhaust, characterized in that the amount of circulation is controlled so that the temperature of the liquid heat medium is below a set temperature. The method for recovering heat from air-conditioning exhaust according to claim 1, wherein the set temperature is determined based on a temperature of outside air. A system for recovering and reusing heat from air-conditioning exhaust,
A heat exchanger capable of gas-liquid contact in a container and exchanging heat between gas and liquid;
A watering part for spraying the liquid heat medium toward the inside of the container, and a receiving part for receiving the sprayed liquid heat medium;
A coil installed in the flow path of the intake air;
A forward path of the liquid heat medium formed between the receiving part and the coil, and a return path of the liquid heat medium formed between the coil and the watering part,
A pump provided in the forward or return path;
A flow controller provided in the forward or return path;
A temperature sensor that is provided in the forward path or return path and measures the temperature of the liquid heat medium;
A control device for controlling the flow rate regulator so that the temperature of the liquid heat medium measured by the temperature sensor becomes a preset temperature,
Air recovery exhaust heat recovery system.

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