JPH1163688A - Method of setting refrigerant evaporation pressure corresponding to load of freezing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of setting refrigerant evaporation pressure and freezing equipment in which a heater and a moistering apparatus are constructed into small capacity ones and which are inexpensive in the installation cost and the running cost. SOLUTION: In a method of setting refrigerant evaporation pressure of freezing equipment having a function to adjust evaporation pressure of a refrigerant, from temperature adjusting set temperature T1 of a fluid to be cooled, a value ΔT obtained by subtracting present evaporation temperature TE from temperature TA of the fluid to be cooled or a value fixed by set temperature, a coefficient Y taking a value larger than O but less than 1, and a percentage X of a cooling output of a freezer evaporation pressure adjusting evaporation temperature T is calculated following: T=T1 -ΔT 1-Y(100-X)/100, and evaporation pressure is set using an evaporation pressure table of a refrigerant used from the evaporation pressure adjusting set temperature T.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for setting the evaporation pressure of a refrigerant in accordance with a load in a refrigeration facility having a function of adjusting the evaporation pressure of the refrigerant.

[0002]

2. Description of the Related Art Some conventional refrigeration systems have a function of adjusting the evaporating pressure of a refrigerant (EPR function). The difference Δt from the evaporation temperature is previously fixed under each temperature condition based on a graph as shown in FIG. 2, and the evaporation temperature of the refrigerant is obtained by subtracting Δt from the set temperature, that is, the temperature at which the fluid to be cooled is to be cooled. The refrigerant evaporation pressure has been set using a vapor pressure table (not shown) of the refrigerant used based on the evaporation temperature.

[0003] Specifically, if the set temperature is -40 ° C,
Since Δt is 3 ° C. from the graph shown in FIG. 2, the required evaporation temperature is −43 ° C. Similarly, if the set temperature is −10 ° C., the Δt is 5 ° C., and the evaporation temperature is −15 ° C.

When the load decreases, the cooling output of the refrigerator decreases, but if the set temperature does not change, Δ
Since t is fixed, the evaporation temperature does not change. Therefore, since the temperature of the air to be cooled, for example, the air blowing temperature, is lowered and supercooled, the set temperature is maintained by heating the cooled air with a heater such as an electric heater.

[0005]

However, in the prior art described above, the heating output of the heater must be increased as the size of the refrigeration equipment increases, and therefore, a heater having a large capacity must be used. In addition, there is a problem in that the equipment cost and running cost increase.

For example, when convection air of 1000 m ³ / min is supplied to a cooled room for circulating a maximum of 3000 m ³ / min of air, the number of objects to be cooled is reduced inside the cooled room, and the load is reduced. If it is cooled, 1000 × 60 × 1.2 × 0.24 × 3 ° C. = 51840
kcal / H Therefore, 51840 ÷ 860 = 60 kW of heating energy needs to be output by the heater.

Further, even when humidity control is performed, since the evaporation temperature does not change when the load is reduced, the air to be cooled is supercooled to cause excessive dehumidification, and the set humidity is maintained. Therefore, the amount of humidification added by the humidifier also increases, and the capacity of the humidifier must also be increased, and there is also a problem that equipment costs and running costs increase.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and can reduce the capacity of a heater and a humidifier so that the equipment pressure and the running cost can be reduced. It is an object to provide a method and a refrigeration facility.

[0009]

In order to achieve the above object, a first aspect of the present invention is a method of setting a refrigerant evaporation pressure of a refrigeration facility having a function of adjusting a refrigerant evaporation pressure.
Temperature control set temperature T ₁ of the fluid to be cooled, the coefficient takes the current evaporation temperature T _E to a value obtained by subtracting or setting temperature by a fixed value [Delta] T, greater value of 1 or less than 0 from the temperature T _A of the cooling fluid Y From the cooling output percentage X of the refrigerator, an evaporation temperature T for evaporating pressure adjustment is calculated by T = T ₁ −ΔT {1-Y (100−X) / 100}, and the set temperature T for evaporating pressure adjustment is calculated. A method for setting a refrigerant evaporating pressure corresponding to a load of a refrigeration facility, wherein the evaporating pressure is set using a vapor pressure table of a used refrigerant.

Further, according to the present invention, the refrigerant pipe between the refrigerator and the evaporator is provided with a control valve for controlling the evaporating pressure in the evaporator and the temperature T of the fluid to be cooled.
A temperature sensor for detecting the _A, setting temperature adjustment of the cooling fluid temperature T _1, the value Δ fixed by the value or the set temperature minus the current evaporation temperature T _E of the temperature T _A of the cooling fluid
From T, coefficient Y that takes a value greater than 0 and 1 or less, and percentage X of the cooling output of the refrigerator, the evaporation temperature T for adjusting the evaporation pressure is calculated as follows: T = T ₁ −ΔT ｛1−Y (100−X) / 100演算, and a calculator for calculating the evaporation pressure using the vapor pressure table of the refrigerant to be used from the set temperature T for adjusting the evaporation pressure, and the control valve of the control valve is controlled by the evaporation pressure setting signal output from the calculator. A refrigeration facility characterized in that the opening degree is adjusted and the evaporation pressure is set.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. The refrigeration equipment according to this embodiment uses a fluid to be cooled as air, and cools the inside of a test chamber 1 such as a low-temperature environment test chamber, which is a cooled chamber. 3 is connected to the refrigerant inlet of the evaporator 4, and the refrigerant return pipe 5 from the refrigerant outlet of the evaporator is connected to the refrigerator.

The evaporator 4 sends cold brine to the heat exchanger 7 of the air conditioner 6, and the brine outlet of the evaporator 4 is connected to the inlet of the heat exchanger 7 by a brine forward pipe 9 having a brine pump 8. The outlet of the heat exchanger 7 is connected to the brine inlet of the evaporator 4 by a brine return pipe 10.

In the air conditioner 6, a blower 11 is provided on the upstream side of the heat exchanger 7, and an electric heater 12 and a humidifier 21 are provided on the downstream side.
And connected to the test chamber 1 by the air return path 14,
By driving the blower 11, the air in the test chamber 1 is sent from the air return path 14 into the air conditioner, cooled by the heat exchanger 7, heated by the electric heater 12, and further cooled by the humidifier 2.
After being humidified to the required humidity in step 1, it is returned to the test room 1 by way of the outward air path 13.

A temperature sensor 15 is provided at the outlet of the air outward path 13.
Is provided, and the air temperature, that is, the temperature T _{A of the} fluid to be cooled is detected and sent to the temperature controller 16. Temperature controller 16
Has input means (not shown) for setting an arbitrary set temperature T ₁ (set temperature for adjusting the temperature of air at the outlet),
This temperature controller has a temperature T _{A of the} fluid to be cooled and a set temperature T _1.
A cooling output setting signal is sent to the refrigerator 2 based on the difference between the cooling fluid and the cooling output value according to the cooling output setting signal as a percentage X of the cooling output together with the temperature T _{A of the} fluid to be cooled and the set temperature T _1. Output to

The next data of the evaporator 4 in the evaporator 4 is obtained by calculating the above-mentioned data in the calculator 17 according to the following equation (A).

T = T ₁ −ΔT {1−Y (100−X) / 100} (A) T: Next evaporation temperature T ₁ : Set temperature ΔT: Temperature of the fluid to be cooled T _A −Current evaporation temperature T _E Y: preset more than 0 to less than 1 factor X: cooling output of the refrigerator (%) Note, T = T if the coefficient in the above formula (a) Y became the cooling output X is 0 _This is to prevent the cooling from becoming ₁ and being unable to be performed, and is appropriately determined according to the scale of the refrigeration equipment, etc., for example, Y = 0.9. Also, the current evaporation temperature T
_E does not directly detect the temperature in the evaporator, but substitutes the previous evaporation temperature calculated for setting the current evaporation pressure.

The next evaporation temperature T calculated by the arithmetic unit 17 is converted into an evaporation pressure using a vapor pressure table (not shown) of the refrigerant to be used, and is sent to a pressure control device 18 for controlling the adjustment (EPR) of the evaporation pressure. Evaporation pressure setting signal (ERP setting signal)
The pressure control device 18 adjusts the valve opening of the control valve 19 provided in the refrigerant return pipe 5 based on the EPR setting signal and the evaporation pressure detected by the pressure sensor 18a. The evaporation pressure is set.

Further, even if the refrigerant evaporation pressure is set based on the result of calculating the evaporation temperature by the above equation, a slight decrease in the air blowing temperature may occur. Generates a heating output setting signal that determines the heating output of the electric heater 12, and the signal is sent to the heating control device 20 to control the heating output of the electric heater 12.

In the above embodiment, the coefficient Y in the equation (A) is 0.9, but in other embodiments, the coefficient Y is equal to 0.9.
Values slightly smaller or larger than 9 are possible. That is, if the value is larger than 0 and equal to or smaller than 1, the effect of the present invention can be obtained.

In the above equation (A), ΔT is a value obtained by subtracting the current evaporation temperature from the temperature of the fluid to be cooled. However, ΔT may be the value Δt shown in FIG. The same effect of preventing overcooling as in the above-described embodiment can be obtained.

Further, in the above-described embodiment, the brine cooled in the evaporator 4 is sent to the heat exchanger 7 in the air conditioner 6 by the brine pump 8, but an evaporator is provided in the air conditioner and this evaporator is provided. The refrigerant from the refrigerator 2 may be directly sent to the refrigerator.

In the above-described embodiment, the electric heater 12 is used as the heater. However, another heater can be used as long as the heating output can be controlled.

Further, in the above embodiment, the evaporation temperature T
_E is the evaporating temperature used for the current pressure setting, but is converted from the vapor pressure table of the refrigerant used based on the pressure detected by the pressure sensor 18a, or evaporates to the evaporator 4 separately from the pressure sensor. A temperature sensor for detecting the temperature may be provided to detect the actual evaporation temperature. Although the humidifier 21 is provided in the air conditioner 6 in the above-described embodiment, the humidifier may not be provided in some cases.

[0024]

As described above, according to this embodiment, the load is reduced and the cooling output percentage X of the refrigerator is reduced.
Is smaller, the value in the parentheses in the above equation (A) for calculating the evaporation temperature becomes smaller, and therefore the evaporation temperature approaches the set temperature.

As a result, unnecessary lowering (supercooling) of the air blowing temperature is prevented, so that the capacity of the heater can be reduced, and an energy saving effect can be obtained.

Further, since the humidifier provided for preventing the excessive dehumidification accompanying the supercooling hardly undergoes the supercooling, the capacity can be reduced, and the energy saving effect can be obtained from this. it can.

[Brief description of the drawings]

FIG. 1 is a schematic circuit diagram of a refrigeration facility according to one embodiment of the present invention.

FIG. 2 is a graph used to determine a refrigerant evaporation temperature for setting a refrigerant evaporation pressure in the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Test room 2 Refrigerator 4 Evaporator 6 Air conditioner 7 Heat exchanger 11 Blower 12 Electric heater 15 Temperature sensor 16 Temperature controller 17 Computing unit 18 Pressure control device 19 Control valve 20 Heating control device 21 Humidifier

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masanobu Ishii 1-50-4 Fujigaoka, Aoba-ku, Yokohama-shi, Kanagawa 202-Iida Corp. (72) Inventor Masahiro Nishihara 1380-4 Mihocho, Midori-ku, Yokohama-shi, Kanagawa

Claims (2)

[Claims] In a method for setting a refrigerant evaporation pressure of a refrigeration facility having a function of adjusting the evaporation pressure of a refrigerant, a set temperature T ₁ for adjusting a temperature of a fluid to be cooled, a temperature T _{A of the} fluid to be cooled, and a current evaporation temperature T _{A. From} the value obtained by subtracting _E or a value ΔT fixed by the set temperature, a coefficient Y that takes a value greater than 0 and equal to or less than 1 and a percentage X of the cooling output of the refrigerator, the evaporation temperature T for adjusting the evaporation pressure is given by: T = T ₁ − ΔT {1−Y (100−X) / 100}, and the evaporation pressure is set using the vapor pressure table of the refrigerant used from the set temperature T for adjusting the evaporation pressure. Corresponding refrigerant evaporation pressure setting method. 2. A refrigerant pipe between a refrigerator and an evaporator is provided with a control valve for controlling an evaporation pressure in the evaporator, and a temperature sensor for detecting a temperature T _A of a fluid to be cooled. setting temperature adjustment of the cooling fluid temperature T _1, the temperature T _a value was fixed by the value or the set temperature minus the current evaporation temperature T _E from ΔT of the cooling fluid, the coefficient takes a large value of 1 or less than 0 Y, From the percentage X of the cooling output of the refrigerator, the evaporation temperature T for adjusting the evaporation pressure is calculated by T = T ₁ −ΔT {1-Y (100−X) / 100}, and the set temperature T for adjusting the evaporation pressure is further calculated. From the vapor pressure table of the refrigerant used, to calculate the evaporating pressure, and the evaporating pressure is set by adjusting the opening of the control valve by the evaporating pressure setting signal output from the operating device. Characterized refrigeration equipment.