JP3471976B2 - Temperature control method of adsorption refrigerator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to temperature control of an adsorption refrigerator.

[0002]

2. Description of the Related Art Adsorption refrigerators are easier to handle than conventional absorption refrigerators and have advantages such as wide allowable temperature range of heat source. It is widely adopted. FIG. 1 shows a schematic structure of an adsorption refrigerator, which includes two heat exchangers A and B used alternately as a regenerator 1a and an adsorber 1b, a condenser 2 and an evaporator 3, and both heat exchangers. In the heat exchanger that functions as the adsorber 1b by switching the cooling water and the hot water supplied to the coils 4 in the exchangers A and B at regular intervals, the solid adsorbent 5 adsorbs the refrigerant (steam), and the regenerator 1a. In the heat exchanger that acts as a unit, the solid adsorbent 5 is made to release the refrigerant, and as shown in the figure, the regenerator 1a and the condenser 2, and the adsorber 1b and the evaporator 3 are connected to each other. The refrigerant vapor discharged from the regenerator 1a is condensed by the condenser 2, and the condensed refrigerant water is supplied to the evaporator 3 through the condensed water pipe 6. On the other hand, in the evaporator 3, since the refrigerant vapor is absorbed by the adsorber 1b and the vapor pressure is kept low, the refrigerant water supplied from the condenser 2 evaporates on the surface of the cooled coil 7 and heats vaporization. By depriving it, the load cold water used for cooling or the like is cooled. Silica gel is usually used as the solid adsorbent, and desorption means releasing the refrigerant (water) adsorbed by the adsorbent by heating with warm water.

The temperature at which the loaded cold water is taken out is preferably as low as possible in consideration of applications such as food preservation. However, for example, in order to set the cold water outlet temperature to 3 ° C., the cooled coil 7 of the evaporator 3 is cooled. The surface temperature needs to be about 1 ° C. on average. On the other hand, the adsorbing power of the refrigerant to the solid adsorbent 5 in the adsorption side heat exchanger 1a fluctuates greatly during one operation cycle, and the refrigerant evaporating temperature in the evaporator 3 becomes the lowest with a slight time delay from the peak of the adsorbing power. Therefore, in order to avoid freezing of the surface of the cooled coil 7 at this time, the evaporation temperature detected by the refrigerant evaporation temperature sensor 8 in the evaporator 3 is lower than a preset lower limit value in the past. At times, the cooling water of the adsorption-side heat exchanger 1a is immediately stopped, and the supply of cooling water is restarted when the evaporation temperature rises to a certain value, thereby coping with fluctuations in the cooling water load and fluctuations in the cooling water temperature. Was.

[0004]

However, considering the year-round operation for expanding the use of the refrigerator to the use other than the cooling, especially in the winter, the temperature of the cooling water is lowered and the inclination of the peak of the adsorption force is large. Therefore, there is a problem that the control becomes difficult and the protection system for preventing freezing frequently operates to repeatedly start and stop the refrigerator. In view of these problems, the present invention suppresses a rapid increase in adsorption force due to a decrease in cooling water temperature, and can control the adsorption force by appropriately following the refrigerant evaporation temperature. It is an object of the present invention to provide a temperature control method for an adsorption refrigerator.

[0005]

As shown in FIG. 1, a temperature control method for an adsorption refrigerator according to claim 1 of the present invention includes two heat exchangers used alternately as a regenerator 1a and an adsorber 1b. , A condenser 2 and an evaporator 3, and both heat exchangers 1
Cooling water and hot water supplied to the coils 4 in a and 1b are switched every predetermined cycle time to adsorb and desorb the refrigerant to and from the solid adsorbent 5 attached to the periphery of each coil 4, and the condenser 2 The condensed refrigerant is guided to the evaporator 3 through the condensed water pipe 6, and the load cold water is cooled by evaporating on the surface of the cooled coil 7, and the evaporation temperature detected by the refrigerant evaporation temperature sensor 8 in the evaporator 3 Is lower than a preset lower limit value (for example, -0.5 ° C), the cooling water of the adsorption side heat exchanger 1b is immediately stopped and the evaporation temperature is kept at a constant value (for example, 2.5 ° C). In the adsorption type refrigerator that restarts the supply of the cooling water when the temperature rises, the cooling water temperature CT is sampled first after the startup and before the start of the cycle operation, as shown in the flowchart of FIG. C Level (e.g., 26 ° C. or higher, 2
Depending on 6 ° C>CT> 22 ° C, three stages of 22 ° C or less), a cycle time (for example, 11 minutes) or a plurality of desorption times (for example, 11 minutes, which are set shorter than the cycle time in advance)
6 minutes, 4 minutes) is selected, and after the start of the cycle operation, adsorption is performed over the entire cycle period, and desorption is performed only during the desorption time. Further, as shown in the flowchart of FIG. 2, the invention of claim 2 measures the evaporation temperature CC at the beginning of each cycle period (for example, 11 minutes), and this temperature CC is within a predetermined range (for example, -0.5). If the temperature is between 0 ° C and + 0.5 ° C), the desorption time set in advance (for example, 6 minutes) is maintained, and if the temperature CC falls below the predetermined range, the desorption time is kept constant. If the setting is changed so as to be shortened (for example, 1 minute) and the temperature CC rises above the predetermined range, the desorption time is extended by the fixed time (1 minute) within the cycle time (11 minutes). It is designed so that the settings can be changed.

[0006]

When the cooling water temperature is lowered, the downward peak of the refrigerant evaporation temperature during one cycle becomes steep. This is because the adsorbent is rapidly cooled when the desorption cycle is switched to the adsorption cycle. In addition, the rate of increase of the suction force becomes large. On the other hand, if the desorption time during the cycle period is shortened, the refrigerant adsorbed on the solid adsorbent 5 is switched to the adsorption cycle without being completely released, so that the adsorbing power is reduced even if cooled by the cooling water in the next cycle. It does not increase so much, so if the cooling water temperature is constant, the refrigerant evaporation temperature increases. In view of this, the first aspect of the present invention is such that the desorption is interrupted during one cycle period and the desorption time is set in the first operation at the time of startup, in consideration of the seasonal change of the cooling water temperature. is there. Claim 2
Is a system in which the setting of the desorption time can be changed momentarily by following changes in load after startup or changes in cooling water temperature due to day or night or weather.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of an adsorption type refrigerating machine to which the present invention is applied, and the structure and operation thereof are the same as those described in the conventional example, and therefore will be omitted. Refrigerant evaporation temperature sensor 8
Is attached to the side wall surface of the evaporator 3, and the cooled coil 7
It is configured to be able to accurately detect the evaporation temperature of the surface of. When the refrigerant evaporation temperature falls below a preset lower limit value (for example, -1 ° C), immediately stop the cooling water of the adsorption side heat exchanger 1b or reduce the cooling water supply amount to 50%, for example. However, the evaporating temperature is the recovery temperature (usually 2.5
The supply of cooling water is restored when the temperature rises up to about ℃).

FIG. 2 is a flow chart showing an embodiment of the temperature control method according to the present invention. The operation cycle time is set to 11 minutes. In the figure, first, after the refrigerator is started, the cooling water temperature CT is sampled before the cycle operation is started, and the cooling water temperature CT is 26
If it is ℃ or more, the desorption time is the whole cycle time, that is, 1
1 minute, 2 minutes to 6 minutes within the range of 26 ℃ to 22 ℃
If the temperature is 2 ° C or lower, set each to 4 minutes, and then start the cycle operation.

In the operation cycle, as shown in FIG. 1, hot water of about 85 ° C. (usually the waste heat of cogeneration is used) is supplied to the heat exchanger 1a on the regeneration side, and the heat exchanger 1b on the adsorption side is supplied. Is supplied with cooling water having a temperature slightly higher than the ambient temperature, and is communicated with the condenser 2 or the evaporator 3 by valves V1 to V4, respectively. Assuming that the desorption time is set to 6 minutes at startup, the refrigerant evaporation temperature CC in the evaporator 3 detected by the evaporation temperature sensor 8 within the first 3 minutes of the 11-minute cycle period is within a predetermined range ( -0.
If it stays within 5 ° C to + 0.5 ° C), there is no change in the desorption time setting, so it is controlled to maintain the initial 6 minutes, and within the first 3 minutes, the evaporation temperature CC is set to the above predetermined value. If it falls below the range, the desorption time is shortened by 1 minute and the setting is changed to 5 minutes.
Desorption is not performed for a minute, and the supply of hot water to the regeneration side heat exchanger 1a is stopped.

When the evaporation temperature CC further decreases to -1 ° C during this period, the supply of the cooling water to the adsorption side heat exchanger 1b is immediately stopped, but usually 10 to 10 seconds after the cooling water is stopped.
The evaporation temperature recovers to the return temperature in about 20 seconds, and the supply of cooling water is restarted. On the contrary, when the evaporation temperature CC rises above the predetermined range within the first 3 minutes of the cycle period, the desorption time is extended by 1 minute to 7 minutes. If the desorption time is equal to the cycle time, it will not be extended any further.

[0010]

According to the invention of claim 1, by suspending the desorption at an appropriate time during the operation cycle, the inclination of the peak of the adsorption force in the next adsorption cycle is made proper, and at the time of start-up. Since the desorption time is set in the first operation of, there is an advantage that the refrigerant evaporation temperature in the evaporator can be accurately controlled according to a wide range change of the cooling water temperature. According to the invention of Item 2, there is an advantage that it is possible to follow the fluctuation of the load and the change of the cooling water temperature after the start with high accuracy. Therefore, in any case, the low temperature is avoided while avoiding the freezing of the cooled coil surface. It is possible to take out the loaded cold water at the time, and there is an advantage that the use of this type of refrigerator can be expanded to a wide range such as food cooling and storage. In the above embodiment, the temperature of the cold water output is controlled by the refrigerant evaporation temperature in the evaporator, but it may be controlled by detecting the outlet temperature of the load cold water instead of the refrigerant evaporation temperature.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a refrigerator showing an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation of the above.

[Explanation of symbols]

1a regenerator 1b Adsorber 2 condenser 3 evaporator 4 coils 5 Solid adsorbent 6 Condensed water piping 7 Cooled coil 8 Evaporation temperature sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shoji Yamaguchi 4-1-2, Hirano-cho, Chuo-ku, Osaka City Osaka Osaka Gas Co., Ltd. (72) Yasuo Yonezawa, 1-15-10 Himesato, Nishiyodogawa-ku, Osaka No. Nishi Yodo Air Conditioner Co., Ltd. (72) Inventor Hiroki Nakano 1-15-10 Himezato, Nishi Yodogawa-ku, Osaka City Nishi Yodo Air Conditioner Co., Ltd. (56) Reference JP-A-60-11072 (JP, A) Kaihei 5-272833 (JP, A) JP 3-7859 (JP, A) JP 6-257885 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F25B 17 / 08

Claims (2)

(57) [Claims] 1. Two used alternately as a regenerator and an adsorber
Two heat exchangers, a condenser and an evaporator, and the cooling water and hot water supplied to the coils in both heat exchangers are switched at a predetermined cycle time, and the solid adsorbent adhered to the periphery of each coil. In addition to adsorbing and desorbing the refrigerant to the condenser, it guides the refrigerant condensed in the condenser to the evaporator, and cools the load cold water by evaporating it on the surface of the coil to be cooled. When the temperature falls below the preset lower limit, the cooling water of the adsorption side heat exchanger is immediately stopped or reduced, and the supply of cooling water is restored when the temperature rises to a certain value. In the adsorption refrigerator, the cooling water temperature is first sampled after the startup and before the cycle operation is started, and a plurality of desorption times are set in advance shorter than the cycle time according to the cooling water temperature level. One select, after the start cycle operation with causing adsorption over the entire cycle period,
A temperature control method for an absorption refrigerator, wherein desorption is performed only during the desorption time. 2. A device used alternately as a regenerator and an adsorber.
Two heat exchangers, a condenser and an evaporator, and the cooling water and hot water supplied to the coils in both heat exchangers are switched at a predetermined cycle time, and the solid adsorbent adhered to the periphery of each coil. In addition to adsorbing and desorbing the refrigerant to the condenser, it guides the refrigerant condensed in the condenser to the evaporator, and cools the load cold water by evaporating it on the surface of the coil to be cooled. When the temperature falls below the preset lower limit value, the cooling water of the adsorption side heat exchanger is immediately stopped or reduced, and the supply of cooling water is restored when the temperature rises to a certain value. In the adsorption refrigerator, the temperature is measured at the beginning of each cycle time, and if the temperature is within the predetermined range, the desorption time set in advance is maintained and the temperature falls below the predetermined range. If the temperature rises above the above specified range, the desorption time is set to be extended by the above fixed time with the cycle time as the limit. A method for controlling the temperature of an adsorption refrigerator, which is characterized by changing the temperature.