CN2416505Y

CN2416505Y - Controllable temperature steam compressing refrigerating low-temperature test chamber

Info

Publication number: CN2416505Y
Application number: CN 00216552
Authority: CN
Inventors: 崔靖
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-02-23
Filing date: 2000-02-23
Publication date: 2001-01-24
Anticipated expiration: 2010-02-23

Abstract

The utility model discloses a steam compressing type refrigerating low temperature test chamber. The utility model adopts a temperature controller (3) to directly control an electromagnetic valve (5) to control the amount of refrigerant which is supplied to an evaporator (1), and the purpose that the temperature of the low temperature test chamber is controlled is achieved, but not adopts the temperature controller (3) to control the refrigerating output which is counteracted by an electric heater to control the temperature. The utility model has the advantages that one half electric power consumption can be saved, the service load of a refrigeration compressor (9) is relieved, the vibration and the noise of the refrigeration compressor are reduced, and the precision of the temperature control is improved.

Description

The steam compression type refrigerating low-temperature test chamber of controllable temperature

The utility model relates to the Cryo Equipment of in a kind of laboratory product being carried out the controllable temperature of cold performance test, particularly adopts the vapor compression refrigeration mode, cavity is carried out the low-temperature test chamber of cooling by the cooling module evaporator.

This low-temperature test chamber mainly is made up of refrigeration compressor, cold doubtful device, device for drying and filtering, kapillary, evaporator, cavity, thermostat, the temperature sensor and the electric heater that are contained in the cavity.Temperature sensor and electric heater all are electrically connected with thermostat and connect.The cavity in this low-temperature test chamber is made long trough according to the requirement of tested object sometimes and is called the low-temperature test groove, and in addition, other theory structure is basic identical.

When start working in this low-temperature test chamber, the compressed machine compression of cold-producing medium enters condenser, be condensed into high pressure refrigerant liquid after emitting evaporation latent heat, after the device for drying and filtering filtration, through the capillary-compensated decompression, enter evaporation in the evaporator again, behind the absorption evaporation latent heat, become low-pressure refrigerant vapor again, return compressor through air intake duct and finish refrigeration cycle.Evaporator is as direct cooling module, the cold of emitting constantly descends cavity temperature, temperature sensor is passed to thermostat to the temperature signal that records, and when temperature dropped to than the lower slightly little difference of the design temperature of thermostat, thermostat was opened electric heater and begun the low-temperature test chamber is heated.The electric heater capacity of selecting for use during design must also have more than needed so that be enough to offset refrigeration work consumption greater than refrigeration work consumption more than 50 percent.Under the heating of electric heater, cavity temperature is bottom out again, and when temperature rose to than the slightly high little difference of design temperature, thermostat turn-offed electric heater again, so temperature descends again.Open so repeatedly, break, the low-temperature test cavity temperature is fluctuateed in the next little difference range on design temperature, reach the purpose of control temperature.The difference of the value up and down of temperature fluctuation range is referred to as variation.The variation in low-temperature test chamber generally requires below 0.3 ℃.

So little variation can not adopt the mode of directly controlling the refrigeration compressor interrupter duty with thermostat to accomplish that even now can save electric heater.This is because the working method of little variation will make refrigeration compressor shut down too continually and start.Even if mini-type refrigeration compressor starts once more after the shutdown and at least also wants after 3 minutes, Fraquent start will burn compressor electric motor because of starting current is excessive.If agree strengthen the temperature variation, such as more than 4 ℃, then can be with the method temperature control of refrigeration compressor interrupter duty refrigeration, such as commercial refrigerator and refrigerator.But so big variation can preserved food products, but can not satisfy the requirement of test apparatus.So temperature control can only be come with the way that electric heater is offset refrigeration work consumption in present low-temperature test chamber.Its advantage is that variation is little, but weak point is the waste of power.In addition, also because refrigeration compressor contends with heating power constantly and is in the state of operating at full capacity, and this state is influential to the mission life of refrigeration compressor always, the vibrations of the state of operating at full capacity and noise are also much bigger than light load state.

The purpose of this utility model is to provide a kind of power consumption low, and vibrations and noise are little, the low-temperature test chamber that temperature-controlled precision is high.

For achieving the above object, the scheme that the utility model adopts is directly the refrigerating capacity in low-temperature test chamber to be controlled by thermostat.In other words, cancel electric heater exactly, directly control the refrigerant flow that enters the cooling module evaporator by thermostat.Specific practice is, add a solenoid valve by thermostat control between device for drying and filtering and kapillary, the feed tube of solenoid valve is connected with device for drying and filtering, and drain pipe is connected with kapillary, thermostat is supplied with the cold-producing medium of evaporator by solenoid control, reaches the purpose of control cold.Adopting the small electrical magnet valve is good selection, and the residue hydrops is few because have no progeny in little solenoid valve pass.The rated power of this small electrical magnet valve generally has only several watts, and dropout current is very little, can save the auxiliary reclay that originally cut-off electric heater.In addition, in the quiescent interval of closed electromagnetic valve, refrigeration work is bordering on and stops, although refrigeration compressor still turns round, its load greatly reduces, and is about half of operating at full capacity, and this is because its air capacity reduces sharply delivery temperature is greatly descended.Because condenser has bigger thermal capacity.When solenoid valve is opened again, when beginning very brief refrigeration, its temperature can not rise very high immediately.So the total medial temperature of condenser can be lower than original temperature.Discharge pressure is directly proportional with condensing temperature, so refrigeration compressor is in the low brisk running status of discharge pressure, and power consumption reduces, and vibrations and noise be decline thereupon also.

Be noted that original low-temperature test chamber considers the thermal inertia of electric heater, thermostat has the PID regulatory function during design.And evaporator also has certain " cold inertia ", so thermostat of the present utility model also should have the PID regulatory function.In order further to improve precision, a small power electric well heater must be installed in cavity, and it and original electric heater have essential distinction, at first, it is original about 1/10th that its power has only, and it is to be used for further offsetting overshoot that " the cold inertia " of evaporator cause.Secondly, it switch on always heating rather than do not stop, disconnected.And after dropping to the temperature control scope, temperature in the cavity just begins to heat.

Also be noted that, for obtaining to be lower than negative low temperature below 36 ℃, refrigerating part is generally made cascade refrigeration, at this moment between the filtrator and kapillary in the middle of solenoid valve should be installed in behind the heat-exchanger rig condenser/evaporator, condenser/evaporator is the evaporator of previous stage and the condenser of back one-level, first-stage condenser after it freezes with the previous stage evaporator.That is to say that solenoid valve connects the filtrator of the condenser back of back one-level.At this moment the kapillary of solenoid valve back still leads to certainly and to be used for the evaporator of refrigeration low-temperature test cavity.

In sum, it is original about 40 percent to adopt total power consumption in the low-temperature test chamber of improvement project to reduce to, and compressor behavior is good, vibrations are little, noise is low, temperature-controlled precision is high.Increased solenoid valve but save electric heater and auxiliary reclay, cost can not improve.

Below in conjunction with drawings and Examples the utility model is described in further detail, accompanying drawing is the structure cut-open view of the utility model embodiment.

Cooling module evaporator [1] and temperature sensor [4] are housed in the cavity [2].The temperature signal that temperature sensor [4] will record in the chamber is passed to thermostat [3], and the solenoid of solenoid valve [5] and thermostat [3] are electrically connected, and controlled by it.The gas outlet of refrigeration compressor [9] leads to condenser [7], the drain pipe of condenser [7] connects device for drying and filtering [8], the feed tube of another termination solenoid valve [5] of device for drying and filtering [8], the drain pipe of solenoid valve [5] communicates with kapillary [6], kapillary [6] other end leads to evaporator [1], the air intake duct of the logical refrigeration compressor [9] of the muffler of evaporator [1].Heat-insulation layer [11] wraps in cavity [2] outside.The heating part of small power electric well heater [10] is in cavity [2], the power of miniwatt well heater [01] is about about 1/10th of refrigeration work consumption, its effect is in order to offset evaporator [1] " cold inertia ", it is heating always after cooling arrives the temperature control scope, rather than interrupted heating.The temperature signal control electromagnetic valve [5] that thermostat [3] records according to temperature sensor [4] reaches the purpose of control evaporator [1] refrigerating capacity to the cold-producing medium quantity delivered of evaporator [1].Small arrow indicates the circulation trend of cold-producing medium among the figure.The refrigeration cycle process is the same with original process, no longer repeated description.If the cascade refrigeration form, then condenser [7] is not by fan cooled, but makes the one of heat interchange mutually with the evaporator of prime refrigeration system, by the prime evaporator cools.For the purpose of simple and clear, the prime refrigeration system has not just been represented on figure.

Make a combination for the refrigerating part that will comprise evaporator [1], again cavity [2] heat-insulation layer [11] etc. is made the split type low-temperature test chamber of another combination, can adopt scheme of the present utility model equally.At this moment solenoid valve [5] is placed on refrigerating part, it is relatively good that temperature sensor [4] and small power electric well heater [10] are placed on cavity [2] part.As for thermostat [3] then be placed on which part can, the way that is electrically connected employing connector group of thermostat [3] and solenoid valve [5] and miniwatt well heater [10].Evaporator [1] can be rendered in the cavity [2], can take out again.Bulky low-temperature test chamber is made split type suitable especially.Put and transport because it is convenient to the laboratory.

Claims

1, a kind of steam compression type refrigerating low-temperature test chamber of the controllable temperature of forming by cavity, evaporator, refrigeration compressor, condenser, device for drying and filtering, kapillary, temperature sensor and thermostat, it is characterized in that: its device for drying and filtering [8] back behind condenser [7] is connected to a solenoid valve [5], the inlet of solenoid valve [5] connects device for drying and filtering [8] and liquid outlet connects kapillary [6], and the test cavity temperature that thermostat [3] records according to temperature sensor [4] comes the cold-producing medium quantity delivered of control electromagnetic valve [5] to evaporator [1].

2, the steam compression type refrigerating low-temperature test chamber of controllable temperature according to claim 1 is characterized in that: a small power electric well heater [10] also is housed in cavity [2], and its power is 15 5 percent to 1 of refrigeration work consumption.