JPH0136017Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a greenhouse heating device configured to forcefully circulate hot water using a pump between a heat source device that utilizes engine exhaust heat and a natural heat radiator in the greenhouse.

Conventionally, in the above-mentioned devices, the control means for maintaining the temperature inside the greenhouse at a set temperature is to turn on/off a heat source device that uses engine exhaust heat in response to room temperature fluctuations, and to keep the engine in an efficient operating state (prevention of overheating, etc.).
In order to achieve this, it was considered to combine engine speed control to maintain the hot water temperature at the outlet of the heat source device at a set value. However, in greenhouse heating systems that use natural convection and have heat dissipation pipes installed indoors, the engine speed is not controlled in response to the indoor heat load, and the engine speed repeatedly starts and stops due to room temperature fluctuations. This resulted in shortcomings such as premature wear of the engine starter and premature deterioration of the battery.

The reason why the above operation is performed can be seen in the correlation with the heat radiation characteristics A of the radiator (radiation tube), the heat loss characteristics B of the greenhouse, and the capacity characteristics C of the heat source device at each rotation speed of the engine, as shown in Figure 3. Consider.

Now, assuming that the room temperature is a constant value, there is a parallel state in which the heat radiation Q _RA of the radiator, the heat loss Q _R of the greenhouse, and the heating capacity Q _HP of the heat source device are equal to each other (Q _RA = Q _R
= Q _HP ), and the operating state of the heat source device that utilizes engine exhaust heat is given as the intersection of characteristics A and C. Further, when the outlet hot water temperature is the set temperature T _W and the outside temperature T _ab , the heat source device is in a parallel operation state at point a.

If the outside temperature rises from T _ab to T _ab ' from this state, the heat loss in the greenhouse will decrease from Q to Q', and if the operating state of the heat source device follows the load, it will move to point b. There must be. However, due to the characteristics of the radiator, the outlet hot water temperature actually moves to point C and decreases to T _W ', so it returns to point a along characteristic A. Therefore, in actual operation, even if the outside temperature rises, the operating state is maintained at point a, which corresponds to excess capacity (Q-Q'), so when the room temperature rises and reaches the upper limit of the setting range, the heat source When the device is stopped and the room temperature falls below the set range, the heat source device is restarted. In other words, even if the outside temperature changes, the engine is operated at full power at point a, and the rotational speed does not change.

The present invention aims to eliminate the above-mentioned drawbacks of conventional operation, and aims to provide a greenhouse heating system that can perform continuous and stable operation at low running costs by controlling the engine speed according to the heat load. It is something.

In order to achieve the above object, the present invention includes means for controlling the engine speed to increase or decrease so as to maintain the outlet hot water temperature of the heat source device using engine exhaust heat at a set value, and a sensor for detecting the outside air temperature of the greenhouse. The apparatus is equipped with circulation amount control means for reversibly reducing the circulation amount by the pump as the outside air temperature rises.

Therefore, the present invention provides the following effects. In the greenhouse heating device of the present invention, when the outside air temperature increases (or decreases) from a certain parallel operation state, the set value of the outlet hot water temperature is automatically decreased (or increased). As a result, the engine speed is controlled to decrease (or increase) as the outlet hot water temperature setting is changed, and the heat source device that uses engine exhaust heat is frequently started and stopped even in response to load fluctuations at low loads. This makes it possible to perform continuous and stable operation according to the load. In particular, in this invention, in order to enable engine speed control according to the load,
Since the system is configured to increase or decrease the amount of hot water circulated by the pump, the operating power of the pump can be saved compared to, for example, a system in which the pump pumps a fixed amount of hot water and adjusts the amount supplied to the greenhouse using bypass flow control. This has the advantage of reducing the running cost of the greenhouse heating system.

Hereinafter, embodiments of the present invention will be described based on the drawings.

Figure 1 shows a schematic configuration of the entire greenhouse heating system, in which reference numeral 1 is the greenhouse, 2 is a heat radiation pipe as a natural radiator laid between crop cultivation furrows, 3 is a heat pump that uses engine exhaust heat, and 4 is a heat pump that uses engine exhaust heat. is a pump for forced circulation of hot water.

The heat pump 3 includes a refrigerant compressor 6 and a condenser 7 driven by an engine 5, an expansion valve 8, and a pump 9.
An evaporator 1 whose heat source water is well water 10 supplied by
1. It is composed of a first heat exchanger 12 whose heat source is hot water heated by engine cooling, and a second heat exchanger 13 whose heat source is engine exhaust gas. The water introduced by the pump 4 is heated by flowing through the condenser 7, the first heat exchanger 12, and the second heat exchanger 13 in this order, and then is supplied and circulated to the radiator 2. .

A temperature sensor _S1 is provided near the hot water outlet of the heat pump 3, and the speed regulating mechanism 14 of the engine 5 is controlled by a control circuit 15 so as to maintain the outlet hot water temperature at a constant value.

The pump 4 uses a pump that can change the pumping amount by controlling the rotation speed of a drive motor, and the rotation speed of the pump 4 is controlled based on the detection result of an outside air temperature sensor _S2 installed near the greenhouse 1. Control circuit 1
Connected to 5. With this configuration, as the outside air temperature increases (or decreases), the pump rotational speed decreases (or increases) according to a preset characteristic, thereby decreasing (or increasing) the circulating amount of hot water at a constant temperature.

Therefore, when the outside air temperature rises (or falls), the pump rotation speed is reduced (or increased) and the amount of heat radiated by the radiator 2 is reduced (or increased). As a result, the return hot water temperature to the heat pump 3 increases (or decreases), and the outlet hot water temperature also increases (or decreases). The engine speed decreases (or increases) to maintain the outlet hot water temperature at the set value T _W
controlled. For example, in Figure 3, the outside temperature is
When there is an upward change from T _ab to T _ab ′, the characteristic of the amount of heat released by the radiator changes from A shown by the solid line to A′ shown by the broken line due to the decrease in the rotation speed of the pump 4, and the outlet hot water temperature changes. In order to maintain the set value T _W , the engine speed decreases from n to n' and enters a parallel operation state at point b.

FIG. 2 shows another embodiment, in which a plurality of pumps 4 arranged in parallel are used as a means to increase or decrease the amount of hot water circulated by the pumps according to changes in outside air temperature.
The system is configured to increase or decrease the number of operating vehicles.

Note that although reference numerals are written in the claims section of the utility model registration for convenience of comparison with the drawings, the present invention is not limited to the structure of the attached drawings by such entry.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram showing the entire greenhouse heating equipment, Figure 2 is an overall schematic configuration diagram of another example, and Figure 3 shows the heat radiation characteristics of the radiator, the heat loss characteristics of the greenhouse, and the heating capacity characteristics of the heat pump. FIG. 1... Greenhouse, 2... Heat radiator, 3... Heat source device using engine exhaust heat, 4... Hot water circulation pump, S ₂
...Outside temperature detection sensor.

Claims (1)

[Scope of utility model registration request] In a greenhouse heating system in which hot water is forcedly circulated by a pump 4 between a heat source device 3 that uses engine exhaust heat and a natural heat radiator 2 in a greenhouse 1, the outlet hot water temperature of the heat source device 3 that uses engine exhaust heat is means for controlling the engine speed to increase or decrease so as to maintain it at a set value, and a circulation system that detects the outside air temperature of the greenhouse 1 with a sensor S ₂ and reversibly reduces the circulation amount by the pump 4 as the outside air temperature rises. A greenhouse heating device characterized by being equipped with a quantity control means.