JPH0138226B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a solar water heater comprising a heat collecting circuit that collects solar heat and solar heat, and a hot water heating circuit that heats water using the collected heat. It is something.

Conventional Structure and Problems Conventionally, this type of solar water heater exchanges heat with the condenser and a heat collection circuit that connects a finch-tube type heat collector, an accumulator, a compressor, and a condenser refrigerant flow control valve. It consists of a hot water heating circuit consisting of a heat exchanger, a pump, and a heat storage tank. In the solar water heater, the refrigerant evaporation capacity of the collector changes due to instantaneous changes in solar radiation or wind speed during operation, so the refrigerant flow control valve supplies an appropriate amount of refrigerant to the collector. That was the problem. This includes the contradictory factors of system stability and operational efficiency.If the degree of superheating of the refrigerant is reduced in order to increase operational efficiency, a hunting phenomenon occurs in the refrigerant flow control valve, and it is necessary to prevent the hunting phenomenon. The content is that if the degree of superheat is set high, the operating efficiency will decrease. As a general measure against these problems, for example, in a thermostatic expansion valve which is one of the refrigerant flow control valves, a heat-shrinkable vinyl is coated on the temperature-sensitive cylinder of the thermostatic expansion valve to improve the responsiveness of the thermostatic expansion valve. However, as shown in Figure 1, which shows the characteristics of the collector outlet temperature change due to changes in the outside air wind speed of a finch-tube type heat collector, the change in the outside air wind speed is instantaneous. The specific number of heat collectors τ _a when the temperature decreases (point a) is smaller than the time constant τ _b of the heat collectors when the outside air wind speed increases (point b). Due to the slow response of the type expansion valve, there was a risk of liquid returning to the compressor if the outside air speed or solar radiation suddenly decreased, which caused problems in terms of load followability and component reliability. .

Purpose of the Invention The present invention solves such conventional problems, and the refrigerant flow control valve appropriately controls the degree of superheating without reducing the operating efficiency of the system and without causing the refrigerant flow control valve to hunt in response to load fluctuations caused by instantaneous changes in solar radiation or wind speed. The purpose is to improve the reliability of the compressor and thermostatic expansion valve.

Configuration of the Invention To achieve this object, the present invention provides a heat collector,
The refrigerant flow rate control of the solar water heater consists of a heat collecting circuit consisting of an accumulator, a compressor, a condenser, and a refrigerant flow rate control valve, and a hot water heating circuit consisting of a heat exchanger that exchanges heat with the condenser, a pump, and a heat storage tank. The time constant in the closing direction of the valve is made smaller than the time constant in the opening direction. A refrigerant flow control valve with the time constant characteristics described above has the following characteristics:
After the valve closes quickly, it slowly shifts to the valve open operation, so it has the ability to follow the load without hunting.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. 1 is a heat collector that evaporates refrigerant using solar heat and atmospheric heat, 2 is an accumulator, 3 is a compressor,
4 is a condenser that condenses the refrigerant, 5 is a temperature-type expansion valve that is one of the refrigerant flow control valves, and 6 is a temperature-sensitive device in which an adsorbent is sealed and the time constant in the opening direction is smaller than the time constant in the closing direction. It is a cylinder, and the above-mentioned 1 to 5 constitute a heat collecting circuit. Further, 7 is a heat exchanger that absorbs heat released from the refrigerant from the condenser 4, 8 is a pump, and 9 is a heat storage tank. Note that 7 to 9 constitute a hot water heating circuit, which together with the heat collecting circuit constitutes a solar water heater.

Next, the operation of the solar water heater having the above configuration will be explained. The high-temperature, high-pressure refrigerant gas compressed by the compressor 3 flows into the condenser 4, and the heat of condensation heats the low-temperature water sent by the pump 8 of the hot water heating circuit, raising the temperature and sending it into the heat storage tank 9. store. On the other hand, the refrigerant, which has been liquefied due to the heat of condensation, flows into the thermostatic expansion valve 5, is depressurized, flows into the collector 1, absorbs solar heat and atmospheric heat, evaporates into gas, passes through the accumulator 2, and compresses the compressor 3.
Return to In the above operation, when instantaneous fluctuations occur in the amount of solar radiation and the wind speed of outside air, the temperature-type expansion valve 5 quickly enters a valve closing operation due to the action of the adsorbent sealed in the temperature-sensitive cylinder 6, causing liquid to return to the compressor 3. When the outlet temperature of the heat collector 1 gradually rises, the time constant in the opening direction of the thermostatic expansion valve 5 is large, so the valve opens slowly, thereby preventing the hunting phenomenon of the heat collecting circuit. be able to.

Effect of the invention The present invention provides a heat collector, an accumulator, a compressor,
In a heat collection circuit in which a condenser and a refrigerant flow control valve are connected, the time constant in the closing direction is set to be higher than the time constant in the opening direction so that the time constant of the refrigerant flow control valve has the same tendency as the time constant of the heat collector. By reducing the
It is possible to prevent hunting in the heat collection circuit due to load fluctuations due to instantaneous changes in solar radiation or outside air wind speed, and prevent liquid return to the compressor or periodic load fluctuations to the compressor motor caused by hunting. At the same time, this has the effect of improving the durability and reliability of the components of the refrigerant flow control valve. In addition, when the load suddenly decreases, the refrigerant flow control valve closes quickly because the time constant is small, which reduces the instantaneous liquid return to the compressor and improves system reliability. There is.

[Brief explanation of drawings]

FIG. 1 is a characteristic diagram of temperature change at the outlet of a finch-tube type heat collector due to changes in outside air wind speed, and FIG. 2 is a configuration diagram of a solar water heater according to an embodiment of the present invention. 1... Heat collector, 2... Accumulator, 3... Compressor, 4... Condenser, 5... Temperature type expansion valve.

Claims (1)

[Claims] 1. Heat collector, accumulator, compressor, condenser,
It consists of a heat collection circuit consisting of a refrigerant flow control valve, and a hot water heating circuit consisting of a heat exchanger, a pump, and a heat storage tank that exchange heat with the condenser, and the time constant of the refrigerant flow control valve in the closing direction is equal to the time constant in the opening direction. A solar water heater with a time constant smaller than . 2. The solar water heater according to claim 1, wherein the refrigerant flow rate control valve is a temperature-type expansion valve.