JPH05231658A - Heat exchanger for refrigerant - Google Patents

Abstract

PURPOSE:To prevent the refrigerant from decomposition, and prevent the heater and pipes from deteriorating by constituting the heater in such a manner that an appropriate superheating of a gas refrigerant may stably be provided. CONSTITUTION:A heater 7 is constituted of a heating passage 3A and a superheating passage 3B, which are put together in two layers and thermally combined. At the heating passage 3A which is the first layer being closer to a combustion burner 1, heat exchanging under a two liquid phase flowing condition is performed, and an indirect heat exchanging is performed at the superheating passage 3B which is the second layer and thermally combined with the first layer, and a gas refrigerant is put under a stable superheating condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant heat exchange device for an air conditioner, which heats the refrigerant by heating means by combustion.

[0002]

2. Description of the Related Art As shown in FIG. 4, a conventional refrigerant heat transfer device is incorporated in an air conditioning system for heating. This system includes a heating channel 33 that is heated by a combustion burner 32 and through which a refrigerant passes, and a heater 36 having an upper header 34 and a lower header 35 that are connected to the heating channel 33.
A separator 38 connected from the upper header 34 of the heater 36 via a discharge pipe 37, a gas pipe 39 through which the gas separated by the separator 38 flows out, and a service valve 40 provided in the middle of the gas pipe 39. And the gas pipe 3
9 and a radiator 41 connected to the gas side cycle. Further, the heater 36 is passed through a liquid pipe 42 through which the refrigerant condensed in the radiator 41 passes, a service valve 43 provided in the middle of the liquid pipe 42, and a refrigerant pump 44 connected to the liquid pipe 42. The liquid side cycle leading to the lower header 35 of FIG. Further, it is composed of a liquid side cycle from the separator 38 to the lower header 35 through the return liquid pipe 45. Furthermore, the return liquid pipe 4
A check valve 46 is inserted at 5. Also, the pump 44
Is controlled by the control means 47.

To explain the operation of the above structure, a constant amount of heat is applied to the refrigerant by the heater 36, and this amount of heat is applied to the radiator 4
When the flow rate of the refrigerant pump 44 is set by the control means 47 so that the refrigerant circulation amount necessary for radiating heat at 1 is generated,
It functions as a refrigerant heat transfer device. Control means 4
7 is the outlet of the heater 36, and has a control method of reducing the refrigerant circulation amount to such an extent that the gas refrigerant is overheated to some extent (for example, Japanese Patent Publication No. 61-15966).

[0004]

However, in the above conventional structure, the heater 36 having a heat transfer surface with a constant heat flux.
However, when the gas refrigerant is overheated, there is a problem that the refrigerant becomes high temperature and decomposes in the overheated region of the heater 36.
When the refrigerant is heated by the heater 36,
The heat transfer coefficient, which indicates the heat transfer state of the heat transfer surface, is significantly reduced in the gas phase region, where the heat transfer coefficient shifts to the gas phase. Therefore, if the heat flux on the heat transfer surface of the heater 36 is constant over the entire area of the heater 36, the temperature of the heat transfer surface in the vapor phase region will rise significantly, and burnout will inevitably occur. Refrigerant, for example 200 for R22
Since decomposition occurs at around 0 ° C, it is necessary to reduce the heat flux in the gas phase region of the heating flow path 33 and keep the heat transfer surface temperature at 200 ° C or lower.

A heater 3 having only a single heating channel 33
The structure of No. 6 has a problem that it is not possible to deal with the problems of heat flux control corresponding to a large decrease in heat transfer coefficient in the gas phase region and the uniformization of the heat transfer surface temperature.

When the refrigerant is decomposed, its thermal properties are changed, and chlorine ions and fluorine ions are generated as decomposition products, and when these are changed to acids, there is a problem that piping is adversely affected. ..

The present invention is to solve the above problems, and when the circulation amount of the refrigerant is set so that the gas refrigerant is appropriately overheated in response to the heat quantity of combustion, the overheating of the gas refrigerant is stable in the heater. It is intended to be done.

[0008]

In order to achieve the above-mentioned object, the present invention comprises a heater comprising two layers, a heating channel and an overheating channel, which are thermally coupled to each other. For heat exchange in the liquid phase and in the two-phase flow in the heating flow path for the second gas, and indirectly for heat exchange in the second layer superheat flow path thermally coupled to the heating flow path for the first layer. The refrigerant is overheated.

[0009]

With the above structure, the present invention performs heat exchange in the liquid phase and the two-phase flow state in the first-layer heating flow path on the burner side of the heater, and thermally separates the heating surface on the burner side sufficiently. Heat flux is 1
In the second layer superheated flow path, which is sufficiently smaller than the first heating flow path,
Since the heat exchange in the gas phase is performed to superheat the gas refrigerant, the gas refrigerant can be heated under the condition that the heat transfer surface temperature is sufficiently controlled, and a desired degree of superheat can be stably obtained.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3, the refrigerant heat exchange device is close to the combustion burner 1 and has a heat exchange fin 2 on the combustion gas side and a passage 2 of the refrigerant thermally coupled to the heat exchange fin 2.
An upper header 4 composed of a heating channel 3A and an overheating channel 3B stacked in layers and connected to the heating channel 3A and the overheating channel 3B, a heating channel 3A and an overheating channel 3
The heater 7 is provided with a lower header 6 that connects B with the partition wall 5 at a distance. The heating channel 3A and the overheating channel 3B are made of a perforated tube made of a material having good thermal conductivity (for example, aluminum) or the like, and are also thermally coupled.

A gas pipe 9 from which the heated gas refrigerant flows out from the lower header 5 of the heater 7 through the discharge pipe 8 and a service valve 10 provided in the middle of the gas pipe 9,
Further, a gas side cycle including a gas pipe 9 and a radiator 11 connected thereto is provided. Further, the heater 7 via the liquid pipe 12 through which the refrigerant condensed in the radiator 11 passes, the service valve 13 provided in the middle of the liquid pipe 12, and the refrigerant pump 14 connected to the liquid pipe 12. The liquid side cycle leading to the lower header 5 of FIG.

In controlling the refrigerant pump 14, first, a standard refrigerant circulation amount corresponding to the combustion amount of the combustion burner 1 is used as an initial value, and the refrigerant pump 14 is supplied with a voltage corresponding to the initial value. At 15, the refrigerant pump 14 is gradually applied. Next, the evaporation temperature T of the refrigerant heated by the heater 7
The temperature c is detected by the temperature detecting element 16 fixed near the inlet of the superheat passage 3B of the heater 7. Further, the temperature Tsh of the refrigerant gas overheated in the superheat passage 3B is detected by the temperature detecting element 17 fixed near the outlet of the superheat passage 3B. The temperature difference determination means provided in the refrigerant pump control circuit 15 detects the temperature difference between Tc and Tsh, and the refrigerant pump control circuit 15 controls the refrigerant circulation amount so that the degree of superheat obtained from this temperature difference becomes a predetermined value. To do.

In order to detect the temperature Tsh of the refrigerant gas overheated in the overheat passage 3B, the temperature detecting element 17 is fixed as close as possible to the overheat region of the overheat passage 3B in order to reduce the delay element of the control system. Is desirable.

The effect of heat exchange in the heater 7 is that when the combustion heat is transferred to the heat exchange fins 2 on the side of the combustion gas provided near the combustion burner 1, the heat exchange fins 2 and the heat exchange fins 2 are thermally coupled. Combined heating passages 3 stacked in two layers through which the refrigerant passes
This heat is transferred to A and the superheat passage 3B. The heat flow path 3A on the combustion burner 1 side has a high heat flux, and latent heat is exchanged with the liquid refrigerant passing through the heating flow path 3A in a two-phase flow state to gasify the liquid refrigerant. The gasified refrigerant is gradually heated in the superheat passage 3B whose heat flux is suppressed by the heat transfer resistance of the heating passage 3A, reaches the lower header 6, and is heated to an appropriate degree of superheat.

In the above configuration, the initial setting of the circulation amount of the refrigerant conveyed by the refrigerant pump 14 is set to the standard refrigerant circulation amount corresponding to the combustion amount of the burner 1, and the superheat passage 3 of the heater 7 is set.
The difference between the temperature of the refrigerant at the inlet of B (evaporation temperature) and the temperature of the refrigerant at the outlet of the superheat passage 3B, that is, the degree of superheat, is controlled to an appropriate value. In addition, the heater 7 has a heating flow passage structure in which the refrigerant passes through two layers, and the latent heat exchange with the liquid refrigerant is performed in the heating flow passage 3A having a high heat flux on the side close to the burner to gasify the liquid refrigerant, It is gradually heated in the superheat passage 3B having a low heat flux to an appropriate degree of superheat.

Further, since the temperature of the heat transfer surface can be controlled stably below the decomposition temperature of the refrigerant, there is no fear of deterioration of the heater and piping due to decomposition products of the refrigerant.

[0017]

As described above, according to the heat exchange device for a refrigerant of the present invention, the following effects can be obtained. (1) A heater is constructed by stacking two layers on a heating channel and a superheating channel, and the first layer heating channel on the burner side ensures heat exchange in a liquid phase and a two-phase flow state with a high heat flux. The heat transfer surface temperature of the gas refrigerant in order to superheat the gas refrigerant by exchanging heat in the gas phase in the second layer superheat passage that is thermally separated from the burner side and has a sufficiently small heat flux. Can be heated under sufficiently controlled conditions. (2) Since the superheat degree is controlled by the pair of temperature detecting elements provided in the vicinity of the superheat passage where the refrigerant gas is gradually heated, the response delay is small and the stable superheat degree is controlled. It is possible. (3) Since the heat transfer surface temperature can be stably controlled to be equal to or lower than the decomposition temperature of the refrigerant, there is no fear of deterioration of the heater and piping due to decomposition products of the refrigerant.

[Brief description of drawings]

FIG. 1 is a partial sectional view of a heater and a burner of a heat transfer device according to an embodiment of the present invention.

FIG. 2 is a refrigerant circuit diagram of the device.

FIG. 3 is a partial cross-sectional view of a heating flow path of a heater of the device.

FIG. 4 is a refrigerant circuit diagram of a conventional heat transfer device.

[Explanation of symbols]

 1 Combustion Burner 3A Heating Channel 3B Overheating Channel 4 Upper Header 5 Partition Wall 6 Lower Header 16, 17 Temperature Detection Element

Claims (2)

[Claims] 1. A heating header and a heating passage through which a refrigerant passes, which is stacked in two layers and is thermally coupled to a combustion burner, and an upper header which connects the heating passage and the heating passage. And a lower header that connects the heating flow path and the superheat flow path with a partition wall therebetween. 2. The heat exchange device for a refrigerant according to claim 1, wherein a pair of temperature detecting elements are provided in the superheat passage.