JPS593337Y2 - solar thermal system - Google Patents

Description

[Detailed description of the invention] This invention relates to a solar thermal system, and particularly relates to a heat collector that converts sunlight into thermal energy and transfers it to a heat collecting medium, and a heat collector that transfers the thermal energy of the heat collecting medium to another heat medium. The present invention relates to a solar thermal system in which a heat exchanger is connected to form a closed circuit, and the heat collecting medium is circulated in the closed circuit.

A solar thermal system of this type having a configuration as shown in FIG. 1 is known.

As shown in this figure, the heat collector 1 converts sunlight into thermal energy and transmits the heat energy to a heat collecting medium flowing inside the heat collector 1.

This heat collector 1 has one end connected to the first stream of a heat exchanger 5 via an inflow pipe 4 equipped with a pump 2 and an expansion tank 3 so that a heat collecting medium in a low temperature state flows in, and the heat collecting medium is The other end is connected to the other end of the heat exchanger 5 via the outflow pipe 6 to make a closed circuit so that the heated heat collecting medium flows out. ).

This heat exchanger 5 is arranged in a heat storage tank 7, and the heated heat collecting medium flowing into the heat exchanger 5 from the outflow pipe 6 is
The thermal energy is transferred to another heat storage medium (in this case water).

) 8, the temperature is lowered, and the fluid flows into the inlet pipe 4.

This heat storage medium 8 is supplied to the lower part of the heat storage tank 7 from a supply pipe 9, and the heat storage medium 8 in a high temperature state that has received thermal energy from the heat exchanger 5 is supplied to the heat storage tank 7. Heat is supplied from the upper part of the heat source 7 to the heat demand location via a supply pipe 11 provided with an auxiliary heat source 10.

However, the reason for such a heat collection circuit (closed circuit) is to prevent freezing, and oil or antifreeze is used as the heat collection medium that circulates in the heat collection circuit. .

Further, the heat collecting medium in the heat collecting circuit is sealed at a constant pressure so as not to suck air from outside the circuit even if its volume changes depending on the temperature.

For this reason, the expansion tank 3 is provided to absorb volume fluctuations due to temperature changes.

The pump 2 is driven by an electric motor 12, which is connected to a temperature detector 13 for detecting the temperature of the heat collector 1 and a temperature detector 14 for detecting the temperature of the heat storage medium of the heat storage tank 7. The operation is controlled by a control device 15 that receives a temperature detection signal from a temperature thermometer or the like.

Note that the auxiliary heat source 10 is a device that brings the heat storage medium to the heat demand temperature when the temperature of the heat storage medium is low.

According to the conventional solar thermal system configured as described above, the electric motor 12 is operated to drive the pump 2 based on the temperature detection signals from the temperature detectors 13 and 14, and the heat collection medium is circulated to collect heat. This is what we do.

In other words, the heat storage tank 7 accommodates the heat storage medium 8 that receives thermal energy from the heat exchanger 3 in which the collected heat collection medium circulates, and the heat storage tank 7 A high-temperature heat storage medium is accumulated on the upper side of the heat storage tank 7, and a low-temperature heat storage medium is accumulated on the lower side of the heat storage tank 7.

In addition, the high temperature heat storage medium stored in the heat storage tank 7 is
The heat is supplied to the heat demand location via a supply pipe 11 connected to the upper side of the heat storage tank 7 and provided with an auxiliary heat source 10 .

Furthermore, the low-temperature heat storage medium is supplied to the lower part of the heat storage tank 1 via a supply pipe 9.

Conventional solar thermal systems operate as described above.

By the way, in the case of the solar thermal system mentioned above, if the heat collection medium leaks in the heat collection circuit, heat collection may become impossible, or
Alternatively, heat collection efficiency may deteriorate.

Further, if the pump 2 is operated idly, it may cause a failure of the pump 2 or the electric motor 12.

Furthermore, leakage of heat collecting media such as antifreeze may have a negative impact on human resources.

For these reasons, it is important to detect leakage.

However, it is difficult to detect leakage of the heat collection medium because the heat collection circuit is a closed circuit as mentioned above, and the volume (pressure) of the heat collection medium fluctuates greatly depending on the temperature within the circuit. The disadvantage was that it was difficult to

This invention was made in order to eliminate the drawbacks of the above-mentioned conventional technology, and it makes it possible to accurately detect leakage of the heat collection medium in the heat collection circuit to prevent deterioration of heat collection efficiency, and to prevent damage caused by leakage. The purpose of the present invention is to provide a solar thermal system that prevents negative effects on energy storage and improves the reliability of the entire system.

To achieve this objective, this invention provides a solar thermal system in which a heat collecting medium circulates in a closed circuit, with a pressure proportional to the temperature of the heat collecting medium and an actually measured pressure of the heat collecting medium. and when the comparison result exceeds a predetermined value, it can be detected that the heat collecting medium is leaking from the closed circuit.

An embodiment of this invention will be described in detail below with reference to the drawings.

FIG. 2 is a schematic piping system diagram showing an embodiment of this invention.

In the embodiment shown in this figure, the same elements as those in FIG. 1 are given the same reference numerals, and their explanations will be omitted.

The embodiment shown in this figure differs from the configuration shown in FIG. 1 in that it includes a temperature detector 16 that can detect the temperature of the heat collection medium circulating in the heat collection circuit and extract it as an electrical signal corresponding to the temperature. A pressure detector 17 which is attached to the outflow pipe 6 and which can detect the pressure of the heat collecting medium and extract it as an electric signal according to this pressure is disposed at the attachment part of the expansion tank of the inflow pipe 4. The electric signal from the surface detector is taken in, and based on the temperature signal from the temperature detector 16, the pressure signal of the heat collection medium at that temperature is determined from preset temperature/pressure correction values, and this pressure signal and the pressure A detection control circuit 18 is provided which compares the pressure signal from the detector 17 and detects that there has been a leakage of the heat collecting medium when the comparison result exceeds a predetermined value, and based on the output of this detection control circuit. The configuration is such that the electric motor 12 (pump 2) and auxiliary power source 10 are stopped, and the alarm 19 is activated to give an alarm.

That is, in the solar thermal system according to this invention, the pressure of the heat collecting medium made of liquid such as oil and antifreeze, which is housed in the heat collecting circuit as a sealed container with a fixed capacity, is adjusted according to the temperature as shown in Fig. 3. Focusing on the change in temperature, the temperature signal T from the temperature detector 16 is taken into the detection control circuit 18,
This signal T is multiplied by a certain correction value α to produce a pressure signal P1(-
αT+B, where B is the origin correction.

), and the pressure signal Px from the pressure detector 17 is obtained.
is taken into the detection control circuit 18, and this detection control circuit 18
, this pressure signal Px and the pressure signal P are compared, and when the comparison result J P = P□ - Px exceeds a predetermined value P5 (in this embodiment, P'x is P.

(when the temperature becomes less than a predetermined value P5), it is determined that there is a leakage of the heat collection medium, and the electric motor 12 (pump 2) and the auxiliary heat source 10 are stopped based on the determination signal from the detection control circuit 18, It is also configured to activate an alarm 19.

According to the solar thermal system configured as described above, the temperature detector 16 detects the temperature of the heat collecting medium circulating in the heat collecting circuit configured by connecting the heat collector 1 and the heat exchanger 5 respectively. , this detected temperature signal T is taken into the detection control circuit 18, and the temperature T is multiplied by a correction value α to obtain a pressure signal P so as to have the relationship shown in FIG.
A control circuit 18 detects the pressure signal Px of the pressure detector 17.
The pressure signal PT is compared with the pressure signal Px, and as a result, when JP exceeds a predetermined value P5, it is determined that the heat collection medium is leaking from the heat collection circuit, and based on this determination result, the heat collection medium is leaked from the heat collection circuit. It is connected to the detection control circuit 18 to stop the electric motor 12 and the auxiliary heat source 10.

Further, an alarm device 19 is used to notify leakage.

Further explanation will be given with reference to FIG.

FIG. 3 is a characteristic diagram showing the relationship between the fluid pressure and the temperature of the heat collecting medium in the heat collecting circuit, where the horizontal axis represents the temperature T ('C) of the heat collecting medium, and the vertical axis represents the pressure P of the heat collecting medium. (kg/c
m2).

As shown in this figure, for example, when the pressure signal Px from the pressure detector 17 is Px □ with respect to the pressure PTI of the heat collecting medium when the detected temperature signal T from the temperature sensor 16 is T1 Then, when the difference exceeds a predetermined value P5, it is assumed that there is a leak.

Therefore, the symbol A is the pressure P at the temperature T of the heat collecting medium.
1 characteristic, and the symbol B indicates the pressure characteristic at which leakage occurs.

In addition, in the above system, the operation of the electric motor 12 and the auxiliary heat source 10 is stopped based on the detection signals from the temperature detector 16 and the pressure detector 17, and the alarm 19 is
However, this may be configured so that only the alarm 19 is operated, or furthermore, the operation of the electric motor 12 and the auxiliary heat source 10 may be stopped without providing the alarm 19. It is.

Further, the temperature detector 16 and the pressure detector 17 may be mounted anywhere in the heat collecting circuit.

As described above, according to this invention, the heat collector and the heat exchanger in the heat storage tank are formed into a closed circuit so that the heat collecting medium circulates, and the pressure of the heat collecting medium in this closed circuit is detected. The system also compares the pressure signal based on the temperature of the heat collection medium and detects leakage when the comparison result exceeds a predetermined value, thereby preventing deterioration of heat collection efficiency and saving energy from human storage. This has the effect of being able to prevent the adverse effects of this, thereby improving the reliability of the entire system.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing a conventional solar thermal system, Fig. 2 is a system diagram showing an example of the solar thermal system according to this invention, and Fig. 3 is a characteristic diagram showing the temperature and pressure characteristics of the heat collecting medium. . 7... Heat storage tank, 5... Heat exchanger, 4.
...Inflow pipe, 1 ... Heat collector, 6 ...
...Outflow pipe, 17...Pressure detector, 19...
...Alarm.

Claims (1)

[Scope of utility model registration request] A heat collector that converts sunlight into heat energy and transfers it to a heat collection medium is connected to a heat exchanger that transfers the heat energy of the heat collection medium to another heat medium to form a closed circuit. In a solar thermal system in which the heat collecting medium circulates in a circuit, a temperature detector detects the temperature of the heat collecting medium in the closed circuit, and a pressure detector detects the pressure of the heat collecting medium in the closed circuit. A pressure signal proportional to the temperature signal from the temperature sensor is compared with a pressure signal from the pressure sensor, and when the comparison result exceeds a predetermined value, the heat collection medium in the closed circuit leaks. What is claimed is: 1. A solar thermal system comprising: a detection control circuit capable of detecting a solar thermal system;