JPS6152914B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heating device that performs heating by driving a compressor using a heat engine powered by combustion energy such as city gas or kerosene.

BACKGROUND ART In recent years, from the viewpoint of energy conservation, there has been active development of air-conditioning and heating devices that perform air-conditioning and heating using heat pumps that use combustion energy such as city gas or kerosene. This heat pump uses combustion energy to operate the engine, etc., which drives the heat pump compressor to perform heating and cooling.The exhaust heat from the engine during heating can be used for heating, so it is more efficient than electric heat pumps. It is energy saving.

However, conventional engine-driven exhaust heat recovery heat pumps have the following problems.

In other words, in conventional heat pumps, when the outside air temperature is very low or when it snows, the evaporation temperature in the outside air side heat exchanger decreases, the specific volume of refrigerant gas increases significantly, and the amount of refrigerant circulated is drastically reduced, resulting in heating. The capacity may drop abnormally and frost may form, making it unusable. In such a case, not only will the heat pump not be able to heat the load hot water, but even if only the engine is operated in an idling state, there is no engine load, so the amount of exhaust heat will decrease, and in the end, the heating capacity will be limited to the outside air that should be pumped. There was a problem in that the reduction in heating capacity due to not only the reduction in heat from the heat pump due to the heat pump being unable to operate, but also the reduction in the amount of exhaust heat from the engine combined with the reduction in heating capacity was significant.

In addition, as a countermeasure against such an abnormal drop in outside temperature, the technology disclosed in Japanese Utility Model Publication No. 51-35632 is also known, but in this case, the technology that prevents engine exhaust when the outside temperature drops abnormally is known. The use of heat is limited to heating the evaporator via outside air, which causes large heat radiation loss, and does not heat the interior air, which is the load fluid, with exhaust heat. The problem is that the amount of heating of the load fluid is small, and the engine exhaust heat is not used when the outside temperature is normal, so exhaust heat recovery is not performed well. It was hot.

There is also a system like the one shown in Utility Model Publication No. 52-22735, but when the outside temperature is normal, heat is not pumped up from the outside air, and the amount of heat recovered is small. In the event that the engine's exhaust heat is abnormally reduced, the use of engine exhaust heat is limited to heating the heat pump's evaporator and does not heat the indoor air, which is the load fluid, and heat is pumped in from the outside air in parallel. The problem was that the amount of heating of the indoor air was small.

The present invention solves the above-mentioned problems of the conventional ones, allows the heat pump cycle to operate even when the outside temperature drops abnormally, prevents frost formation, heats the load fluid, and also operates using waste heat. To provide a heating device that heats a fluid, prevents a decrease in heating capacity, and heats a load fluid using exhaust heat from an engine together with a heat pump even when the outside temperature is normal, thereby improving heat utilization efficiency. This is the purpose.

The present invention includes a compressor driven by a heat engine;
In a heating system having a heat pump cycle consisting of an outside air side heat exchanger, a load side heat exchanger, an expansion device, and a refrigerant path connecting these devices, and a heat recovery device that recovers exhaust heat from the heat engine, during heating. The load fluid is heated by the load side heat exchanger and the heat recovery device, and an auxiliary evaporator is provided as an evaporator in parallel with the outside heat exchanger and is capable of being heated by the load fluid. The heat engine is equipped with a detector that directly or indirectly detects the heat engine, and a rotation speed control mechanism that controls the rotation speed of the heat engine, and in the event of an abnormality such as an extreme drop in outside air temperature, the heat engine rotation speed is higher than the maximum rotation speed under normal conditions. The heating device is characterized in that the set value is changed so that the auxiliary evaporator is operated.

The present invention will be explained with reference to the drawings based on examples.
In the cooling/heating device shown in the drawings, the normal heat pump cycle is similar to that of a general electric air source heat pump. That is, during summer cooling, the refrigerant flows from the compressor 1 → four-way valve 2 → outside air side heat exchanger 3 (operates as a condenser) → check valve 4 → receiver 5 → expansion valve 6 → load side heat exchanger 7 (evaporator). The cold water is circulated in the order of (operating as a heat exchanger) → four-way valve 2 → compressor 1, and the cold water is cooled in the load-side heat exchanger 7.

During heating, the four-way valve 2 is switched to change the path of the refrigerant, compressor 1 → four-way valve 2 → load side heat exchanger 7 (acts as a condenser) → check valve 8 → receiver 5 → expansion valve 9 → outside air side The hot water is circulated in the order of heat exchanger 3 (acting as an evaporator) → four-way valve 2 → compressor 1, and the hot water is heated in the load-side heat exchanger 7.

On the other hand, the cycle on the engine 25 side is as follows. During cooling, exhaust heat from the engine water jacket 11 is cooled by outside air by the coolant cooler 10. That is, the coolant that has been heated by cooling the jacket 11 is sucked by the pump 12, sent to the coolant cooler 10, and cooled there. The water is then supplied to the jacket 11 again via the three-way valve 13. In addition, the temperature detector 24
The temperature of this cooling medium is detected, and the three-way valve 13
The bypass amount of the exhaust heat recovery device 14 is controlled, and cooling water at an appropriate temperature is supplied to the jacket 11.

During heating, the switching valves 15, 17, and 18 are switched, and the solenoid valve 20 is opened, so that exhaust heat from the engine is used to heat hot water. That is, the jacket 11
A part of the hot water, which is the cooling water load fluid, is sucked in by the pump 12, passes through the three-way switching valve 15 and the connecting pipe 16, is heated by the auxiliary evaporator 23, and then passes through the three-way switching valve 17. , and is sent to the heat exchanger of the exhaust heat recovery device 14, where it is further heated by the exhaust gas.

The heated hot water is supplied through a three-way switching valve 18 and a connecting pipe 1.
9, it joins with the hot water from the load-side heat exchanger 7, and is used for load heating. The load hot water whose temperature has decreased passes through the solenoid valve 20 and is used to cool the jacket 11 again. Note that when the load is light, the temperature of the hot water supplied to the jacket 11 may be too high, so the supplied temperature is detected by the temperature detector 24 and adjusted by the three-way control valve 13 so that the temperature is approximately constant.

Further, in the event of an abnormality in which the outside temperature drops abnormally, the outside temperature thermostat is activated and the rotational speed of the engine 25 is switched to be higher than the set rotational speed for heating. At the same time, the bypass valve 21 is opened, and the liquid refrigerant is depressurized by the expansion valve 22, and the cooling water for the engine 25, that is, the load It is heated by some of the hot water and evaporates.
Conversely, the hot water is cooled and the temperature of the hot water exiting the auxiliary evaporator 23 decreases.

However, by heating the refrigerant in the auxiliary evaporator 23, a heat pump cycle is established, frost formation is prevented, the load hot water can be heated in the load side heat exchanger 7, and the engine speed is lower than the set rotation speed during heating. It also operates at high speed and can generate a large amount of waste heat to heat the load hot water.
As a result, the load hot water can be effectively heated, and even if the outside air becomes abnormally low temperature, the heating capacity can be prevented from decreasing.

Note that a rotation speed control mechanism is provided to adjust the rotation speed of the engine 25 in accordance with the load.
For example, the load temperature is controlled to be constant by detecting the load temperature, converting the temperature signal into a voltage signal, sending this voltage signal to the governor, and operating the throttle valve of the engine 25 using the governor motor. It's summery.

Instead of the outside temperature thermostat that directly detects the outside temperature, a suction pressure switch of the compressor 1 or a thermostat that detects the evaporation temperature may be used to indirectly detect the outside temperature. The heating source for the auxiliary evaporator 23 may be direct exhaust gas or hot water at the inlet or outlet of the load-side heat exchanger 7, which acts as a condenser.

According to the present invention, it is possible to provide a heating device having the following particularly remarkable effects.

(1) When the outside temperature drops abnormally, (a) the load fluid and refrigerant are simultaneously introduced into the auxiliary evaporator inserted in parallel with the outside air side heat exchanger used in the case of normal outside temperatures; None, the refrigerant is heated by the load fluid and evaporated to generate a refrigerant gas with a small specific volume, preventing frost formation and enabling the operation of the heat pump cycle. The auxiliary evaporator heats the load fluid and provides the load fluid with a larger amount of heat than the heat removed by the auxiliary evaporator, effectively heating the load fluid.

(b) Since a portion of the load fluid is directly heated by the exhaust heat of the engine, the amount of heating of the load fluid is further increased, and less recovered heat is dissipated.

(c) As shown in (a), by enabling the operation of the heat pump cycle, the engine is operated at or near the rated load rather than idling, resulting in a large amount of exhaust heat. The amount of heating of the fluid becomes large.

(d) At the same time that the auxiliary evaporator heats the load fluid, it is also possible to pump up heat from the outside air in the outside air side heat exchanger, which can increase the amount of heating of the load fluid in the heat pump.

(e) Furthermore, the rotational speed of the heat engine is set to be higher than the maximum rotational speed during steady state to increase the displacement and increase the amount of heating of the load fluid.

(f) In this way, the load fluid is heated as much as possible to prevent a decrease in heating capacity.

(2) When the outside temperature is normal (a) Heat is pumped up from the outside air to activate the heat pump cycle to heat the load fluid, and at the same time heat a part of the load fluid using engine exhaust heat to utilize the heat. It is possible to improve the rate.

[Brief explanation of the drawing]

The drawing is a flow diagram of an embodiment of the invention. 1...Compressor, 2...Four-way valve, 3...Outside air side heat exchanger, 4...Check valve, 5...Receiver,
6... Expansion valve, 7... Load side heat exchanger, 8... Check valve, 9... Expansion valve, 10... Cooler, 11
... Jacket, 12 ... Pump, 13 ... Three-way valve, 14 ... Exhaust heat recovery device, 15 ... Switching valve, 1
6... Connection piping, 17... Switching valve, 18... Switching valve, 19... Connection piping, 20... Solenoid valve, 21...
...Bypass valve, 22...Expansion valve, 23...Auxiliary evaporator, 24...Temperature detector, 25...Engine.

Claims (1)

[Scope of Claims] 1. A heat pump cycle consisting of a compressor driven by a heat engine, an outside air side heat exchanger, a load side heat exchanger, an expansion device, and a refrigerant path connecting these devices; In a heating device having a heat recovery device that recovers waste heat of An auxiliary evaporator that can be heated by a fluid is provided, and is equipped with a detector that directly or indirectly detects the outside air temperature and a rotation speed control mechanism that controls the rotation speed of the heat engine, so that when the outside air temperature becomes extreme, A heating device characterized in that, when an abnormal condition occurs, a set value is changed so that the heat engine rotation speed becomes higher than the maximum rotation speed during normal operation, and the auxiliary evaporator is operated.