JPS602578B2 - Refrigeration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a refrigeration system that can control the humidity of refrigerant gas at the outlet of an evaporator with constant and high precision, maximize the performance of the evaporator, and improve the efficiency of the refrigerating capacity. Regarding the configuration of the device.

Conventional compression refrigeration equipment uses a temperature-controlled variable expansion valve (hereinafter referred to as an expansion valve) to control refrigerant flow rate and to protect against abnormal pressure. The pressure switch was used to protect the discharge gas from abnormally high temperatures, and the discharge pipe thermostat was used to handle each phenomenon. Among these, cold soot flow control using an expansion valve is a method that changes the refrigerant flow rate by detecting the degree of superheating of the refrigerant at the evaporator outlet. Temperature changes cannot be detected unless the degree of superheating at the location is usually 5° C. or higher. On the other hand, most of the compressors currently in use are of the closed type with a built-in motor and low-pressure dome type that cools the motor before the refrigerant reaches the cylinder inlet, so the degree of superheating at the compressor suction port is even higher. There is a problem in that it is impossible to prevent the discharge gas temperature from becoming abnormally high.

Therefore, it goes without saying that even if the evaporator outlet is saturated or slightly humid, it will not have a negative effect on the compressor, and that it is more thermally efficient for the evaporator to run entirely wet. Since no suitable control mechanism has been provided to control wet operation regardless of load fluctuations, the actual situation is that the degree of superheating is controlled using an expansion valve, even though we know it is wasteful.

The present invention deals with this fact, uses a general-purpose expansion valve for superheat degree control, and can control the refrigerant flow rate so that the refrigerant gas condition at the evaporator outlet has a constant humidity level, which solves the conventional problem. The purpose of this invention is to provide a refrigeration system that can easily realize humid operation and improve the efficiency of the compressor. The temperature-sensing cylinder is made up of a control circuit that calculates the degree of dryness of the bracket and emits an output corresponding to the dryness of the bracket, and an electric heater for heating the temperature-sensing cylinder whose heating amount is adjusted according to the output. by detecting a predetermined degree of superheat, the opening degree of the expansion valve is adjusted to match the degree of superheat,
It is characterized by a configuration in which the refrigerant flow rate is adjusted so that the gas condition at the evaporator outlet has a constant humidity level.

The present invention will be further described in detail below with reference to a specific implementation device shown in the accompanying drawings. It is a low-pressure dome-shaped compressor with a discharge port connected to the inlet of the condenser 2, an inlet port connected to the outlet of the evaporator 3 through the inside of the casing, and a connection between the condenser 2 outlet and the evaporator 3.
A known refrigeration circuit is formed by interposing a gas-filled expansion valve 4 in a liquid pipe communicating with the inlet.

The expansion valve 4 is set to a predetermined degree of superheat, for example, 5° C., by attaching a general-purpose temperature-sensitive cylinder 5 as a control element to an appropriate location of the gas pipe 6 from the outlet of the evaporator 3 to the inlet of the compressor 1. It has a similar form to the superheat degree control expansion valve that has been widely used in the past.

As shown in FIG. 2 to FIG. In addition, the pressure of the sealed gas changes under the influence of the temperature of the electric heater 7.

Various configurations can be considered for the arrangement of the electric heater 7, but in the example shown in FIG. This is an example in which the thermosensor tube 5 is provided and fixed by means such as tightening the band B so that the amount of heat generated affects only the thermosensor tube 5.

In addition, the example shown in Figure 3 is one in which a movable electric heater 7 is wrapped around a temperature sensing cylinder 5 and a gas pipe 6 so that the heat generated by the electric heater 7 affects both 5 and 6 at the same time. Furthermore, the example shown in Figure 4 is one in which the temperature sensing cylinder 5 and the gas pipe are wrapped together so that the heat generated by the electric heater 7 affects both 5 and 6 at the same time. In the example shown in FIG.
It is designed to simultaneously exert a thermal influence on the gas pipe and the gas pipe. By taking the form shown in each of the above examples,
The electric heater 7 mainly heats the temperature sensing cylinder 5 so that the pressure of the gas sealed therein is substantially increased compared to the pressure corresponding to the refrigerant temperature in the gas pipe 6.

In order to adjust the calorific value of the electric heater 7, a control circuit 8 is provided in the electrical system that controls the operation of the refrigeration system, and the control circuit 8 includes a calculation section connected to an input terminal,
An output section that generates an output, such as a voltage, corresponding to the signal from the calculation section is an element, and the output voltage is applied to the electric heater at a value that is suitable for the operating conditions of the refrigeration system.

The input signals input to the calculation section of the control circuit 8 are electrical signals corresponding to the following three cooling conditions, namely the evaporation temperature TE of the evaporator 3 and the condensation temperature T of the condenser 2.

The elements are the output signals of each temperature detector that detects three types of temperatures: and the discharge gas temperature TH of the compressor 1. The arithmetic unit is equipped with a memory and a readout unit, and the memory stores in advance each piece of information corresponding to each operating condition of the refrigeration system at respective addresses.

Generally, in refrigeration equipment, the evaporation temperature TE, the condensation temperature T
.

Once the compressor discharge gas temperature TH is known, the cold soot states A to C at each part can be determined on the Mollier diagram in FIG. Cold soot condition 2 subsides. Once the soot state 2 is determined, the degree of dryness X of the refrigerant gas at the outlet of the evaporator 3 can also be easily determined.

Since the above analysis means can be easily performed, the above three elements T8, TC, T in each operating state are stored in the memory.
Each piece of information is stored in a predetermined location, with each group consisting of four values: H and the degree of dryness of the cold soot gas at the outlet of the evaporator 3.

The memory, in which information corresponding to each operating state is stored in this way, receives signals corresponding to the evaporation temperature T8, condensation temperature TC, and discharge gas temperature TH from the refrigeration layer during refrigeration operation. , select the address where the same condition or the most similar condition is stored for these three signals, read out the information corresponding to the dryness x of the predetermined cold soot gas from the address, and output this information to the subsequent stage. Send to the department.

The output section is formed into an operational amplifier circuit that, upon receiving information from the memory, compares a value corresponding to the dryness level X with a value corresponding to a predetermined dryness level and generates an output voltage corresponding to the difference. are doing.

The operating mode of the refrigeration system configured as described above will be explained next with reference to FIG. 6.

During operation of the refrigeration system, when the control circuit 8 is not activated and the electric heater is not energized, the refrigeration system can be operated at a predetermined degree of superheat, similar to known refrigeration systems.

On the other hand, when the control circuit 8 is actuated to energize the L electric heater 7, the temperature-sensitive tube 5 is heated, and the expansion valve 4 opens more, increasing the amount of frozen water passing through the coil of the evaporator 3. A so-called wet operation is performed in which the entire area is in a wet refrigerant state.

If the current applied to the electric heater 7 is selected to an appropriate value in this step, it is possible to stably maintain proper wet operation with the dryness X within the range of 0.85 to 0.9.

That is, as shown in FIG. 6, three detection elements TE, TC,
Calculate the outlet gas dryness x of the evaporator 3 from TH, and if the dryness x is within a predetermined value, the flow to the electric heater 7 will not be changed; By increasing the flow of water to the heater 7 and causing the temperature-sensing tube 5 to sense that the degree of superheat has increased, the degree of opening of the expansion valve 4 is increased to reduce the degree of dryness to a predetermined level. Maintain dryness level X. Furthermore, if the degree of dryness It is possible to increase the degree of dryness x by decreasing the opening degree and maintain it at a predetermined degree of dryness x.

By performing the above control, stable wet operation control is possible while using the superheat control expansion valve regardless of load fluctuations.

As described above, in the present invention, as a control element of the temperature-type variable expansion valve 4, an electric heater T is disposed in a temperature-sensitive tube 5 attached to a cooling pipe extending from the outlet of the evaporator 3 to the compressor 1 so as to be able to conduct heat. By automatically adjusting the heating amount of the electric heater 7 in accordance with the operating state of the refrigeration system, it is sensed as a pseudo change in the degree of superheating of the intake cooling gas. Even if there is a humid inhaled gas soot in an area where there is no pressure change, it is possible to control it to maintain a constant humidity level.
The refrigeration system can be operated in a wet state regardless of the size of the load, and the evaporator 3 can be effectively used at its maximum capacity without having any negative effects such as liquid compression on the compressor, and the refrigeration system can be operated efficiently. can.

Moreover, since this control is possible using a general-purpose gas-filled variable expansion valve 4, it has the advantage of being easily applicable to existing equipment, and can be implemented with almost no modification to the cold soot system. This is a great refrigeration device with great practical value.

[Brief explanation of the drawing]

Each figure shows the aspect of an example of the device of the present invention. Figure 1 is a circuit diagram of the device, Figures 2 to 4 are structural diagrams of the part attached to the thermosensor tube, and in each figure, A is an external view, and the opening is a vertical cross section. Show the diagram. FIG. 5 is a Mollier diagram relating to the device of the present invention, and FIG. 6 is a diagram showing the operating procedure of the control circuit. 1...Compressor, 2
...Condenser, 3 ... Evaporator, 4 ... Temperature-type variable expansion valve, 5 ... Temperature-sensing cylinder, 6 ... Refrigerant cup tube, 7 ... ...Electric heater, 8...Control circuit,
TE...Evaporation temperature, TC...Condensation temperature, TH...
...Discharge gas temperature, X... Evaporator outlet gas dryness. Figure 3

Claims (1)

[Claims] 1. Attach the temperature-sensitive tube 5 of the temperature-type automatic expansion valve 4 to the refrigerant pipe from the outlet of the evaporator 3 to the compressor 1, and attach an electric heater 7 with adjustable calorific value to the temperature-sensitive tube 5 in a thermally conductive manner. On the other hand, the evaporation temperature T_E of the evaporator 3 and the condenser 2
The control circuit 8 has three electric signals as input elements corresponding to the condensing temperature T_C of the compressor 1 and the discharge gas temperature T_H of the compressor 1.
and a calculation unit that calculates the dryness X of the evaporator 3 outlet gas obtained from the Mollier diagram using the discharge gas temperature T_H as a parameter, and increases the output when the dryness X deviates from a predetermined value and increases, and output when it decreases. The electric heater 7 generates heat using the output from the control circuit, and the temperature-sensitive tube 5 is heated, thereby increasing the evaporator 3.
Even though the outlet gas state of the evaporator 3 is humid, the thermosensor cylinder 5 senses a temperature that matches the predetermined degree of superheat, and adjusts the opening of the expansion valve 4, so that the evaporator 3 is substantially closed. A refrigeration system characterized in that it maintains a wet operation.