Refrigeration Laboratory Unit is a fully instrumented refrigerant vapour compression refrigerator with belt driven compressor, electrically heated evaporator, thermostatic expansion valve and water cooled condenser. Refrigeration Laboratory Unit Instrumentation includes all relevant temperatures, condenser pressure, evaporator pressure, refrigerant and cooling water flow rates, evaporator and motor power, motor torque and compressor speed. Operating parameters can be varied by adjustment of condenser cooling water flow and electrically heated evaporator supply voltage. Components have a low thermal mass resulting in immediate response to control variations and rapid stabilisation.
Experimental Capabilities:
Investigation of the variation in refrigerator duty or cooling ability for various condensing temperatures.
Investigation of the variation in refrigeration Coefficient of Performance for the various condensing temperatures.
Production of a vapour compression cycle diagram under various conditions.
Production of an energy balance for the refrigerator.
Investigation of the performance of the thermostatic expansion valve.
Investigation of the heat delivered to the cooling water with variation in condensing temperature.
Investigation of the variation in Coefficient of Performance based on electrical, shaft and indicated power.
Determination of the overall heat transfer coefficient for the condenser cooling coil.
Investigation of power input based on electrical, shaft and indicated power.
Investigation of the Coefficient of Performance as a Heat Pump for various condensing temperatures.
A bench mounted vapour compression Refrigeration Cycle Demonstration Unit using a hermetic compressor and water cooled flooded glass condenser and evaporator. Internal electrical and mechanical safety devices allow for unsupervised operation by students. Standard instrumentation fitted enables measurement of the condenser and evaporator pressures and temperatures as well as water flow rates and water temperatures. A float controlled expansion device controls the flow of refrigerant in the system. Refrigeration Cycle Demonstration Unit operates on low-pressure non-toxic ozone friendly refrigerant.
Experimental Capabilities:
Investigation and demonstration of the pressure-temperature relationship during evaporation and condensation.
Demonstration of the vapour compression refrigeration and heat pump cycle with visual observation of all-important processes.
Demonstration of: -
Determination of effect of evaporating and condensing temperatures on the refrigeration rate and condenser heat output.
Determination of overall heat transfer coefficient in a simple shell and tube type heat exchanger.
Investigation of the effect of compressor pressure ratio on system performance.
Charging
Pumping over or pumping down the refrigerant charge into the condenser.
The effect of air in refrigeration systems.
The Oil Return In Refrigeration Systems is of key importance for the service life of the compressor and thus for a secure constant supply of refrigeration. In the vaporised refrigerant the oil remains liquid in the lower parts of the system. This can result in lack of oil in the compressor. To return the oil to the compressor, a minimum velocity must be maintained in the pipes. A small diameter of the rising pipe results in a high velocity and ensures the return of the oil even under partial load. However, at full load the pressure loss increases due to the small diameter. The velocity in the rising pipe depends on the pipe diameter and the refrigerant mass flow. In most compressors some lubrication oil is carried along with the compressed refrigerant. In the liquid refrigerant the oil is dissolved in the refrigerant and is transported without problems. If the velocity in the rising pipe on the intake side of the compressor is too low (partial load), the oil is not returned to the compressor due to its higher density.
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Refrigerator Repair And Training Equipment Direct Cooling can be used to train students to master the theoretical knowledge and practice skills of direct cooled refrigerator system.
The control panel wiring connection diagram panel with test points in the circuit diagram, it is easy for students to measure and debugging.
Structure And Compositions:
Mobile aluminum profile frame with control panel:
Control panel wiring connection diagram panel,
Refrigerators refrigeration schematics panel,
Fault setting panel.
Refrigeration systems with two-stage compression are used for the generation of particularly low temperatures. Therefore, two compressors are connected in series, with each compressor only having a relatively low pressure ratio. At very low temperatures large pressure differences are required between the evaporator and condenser. In a compressor the volumetric efficiency drops significantly at high pressure ratios. In addition, intercooling between the low pressure compressor and the high pressure compressor reduces the outlet temperature of the compressor to harmless values and improves the efficiency of the compression. This makes a more favourable dimensioning of the low pressure stage compressor possible. Due to the large specific volume it requires a larger capacity at lower drive power.
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This climate depends on different influences, such as the surface temperature of the evaporators, cold storage room temperature, degree of evaporator icing, quantity and type of refrigerated goods etc. Icing of the evaporators significantly reduces the refrigeration capacity and must therefore be prevented as much as possible by periodic defrosting, i.e. heating the evaporator surfaces. The climate in the cold storage room has a significant effect on the quality of the products stored there. The icing of the evaporators depends on the evaporator and room temperatures and the quantity of humidity introduced by the refrigerated goods. The evaporator surface can be heated from the outside by electric heating or from the inside by hot gas directly from the refrigerant compressor. In addition to the periodic defrosting at set times, there is defrosting performed as required by measuring the actual ice coating.
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The super Heater included in the set is a heat exchanger ensuring the complete evaporation of the refrigerant before entering the compressor whilst the liquid refrigerant is supercooled upstream of the expansion element. The set includes simple refrigeration components, such as expansion elements and filters, as well as electrical components, e.g. switches and thermostat. Via pressure and temperature measurements the change of state of the refrigerant can be tracked and entered. The temperature is measured by interlaboratory thermometers. The control behaviour of the expansion element is monitored at the flow meter. Manometers provide an insight to the pressure ratios in the refrigeration circuit.
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Commercial components are used in practical experiments. These components are mounted on plates ready to be connected and are arranged clearly in the frame. This allows for the defrosting of an iced-up evaporator by operating it temporarily as condenser. Manometers provide an insight to the pressure ratios in the refrigeration circuit. The set includes complex refrigeration components, such as capacity controller, start-up controller, defrost timer, 4/2-way reversing valve and refrigeration controller. The 4/2-way reversing valve, for example, is used to reverse the circuit.
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The model is plugged onto the base unit, secured using fasteners and connected with refrigerant hoses to become a complete refrigeration circuit. In refrigeration and freezing combinations evaporators are preferably connected in parallel. This is part of the training system for refrigeration and air conditioning technology. To increase the refrigeration capacity, evaporators are operated connected in series. Here different pressure levels in the evaporators can be used to obtain different temperature ranges for refrigeration or freezing. In combination with the base unit the operational model of a refrigeration system with refrigeration and freezing stage results.
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Commercial Refrigeration Unit With Fault Simulation device can be used to train students to master the theoretical knowledge and practice skills of the commercial refrigeration system.
Features:
Selection of cooling stage via solenoid valves
Semi-hermetic piston compressor, air-cooled condenser
Mobile refrigeration unit with normal cooling stage and deep-freezing stage
Individual and parallel operation of the cooling stages possible
All fans are speed-controlled
Cooling stages: insulated chambers with air-cooled evaporators
Built in faults set module.
Absorption refrigeration systems operate using thermal energy. This basic principle is demonstrated in the experimental unit with the example of an ammonia-water solution with the ammonia acting as refrigerant. They use the principle of liquids evaporating already at low temperatures when pressure is reduced. In the evaporator the liquid ammonia evaporates and withdraws heat from the environment. To keep the evaporation pressure low, the ammonia steam in the absorber is absorbed by the water. For this purpose, the high concentration ammonia solution is heated in a generator until the ammonia evaporates again. In the final step, the ammonia steam is cooled in the condenser to the base level, condenses and is returned to the evaporator. The low concentration ammonia solution flows back to the absorber. To maintain the pressure differences in the system, hydrogen is used as an auxiliary gas. In the next step, ammonia is permanently removed from the high concentration ammonia solution to prevent the absorption process from being halted.
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The refrigeration circuitry includes a water cooled condenser complete with isolating valves, manual expansion valve, evaporator, variable area flowmeter for mass flow of refrigerant, filter/drier unit, sight glass and over pressure cut-out for unit protection. The unit is designed to use Tetrafluoroethane as the refrigerant with a twin cylinder reciprocating compressor, belt driven by the variable speed dynamometer.
The evaporator coil is mounted in an electrically stirred water/glycol mixture contained in a thermally insulated, stainless steel tank. The water/ glycol mixture is protected from over temperature conditions by a thermostat should the heater should be left on when the compressor is not circulating refrigerant. Heating of this water/glycol mix is infinitely variable enabling balanced experimental conditions over a wide range of temperatures to be obtained.
Experimental Capabilities:
Determine the Mechanical, Thermodynamic (Isentropic) and Volumetric efficiencies.
Estimate the rate at which heat is transferred to the system from the surrounding environment.
Determine the energy flows and coefficient of performance for given operating instructions.
Operate the refrigeration unit over a range of conditions.
Estimate the Heat Transfer Coefficient.
Compile an energy balance under light load and full load conditions.
Examine the behaviour refrigerating cycle under variable loads and speeds.
Features:
Portable and easy to carry
Built in safety valve manifold compound and pressure gauges
Vacuum gauge hose ccl-36 (90cm) with safety goggles and oil for vacuum pump
Compressor power: 280W
Rotary vane type with two stage vacuum pump
With a digital scale (up to 100 Kg with a 0.5% accuracy)
Vacuum pump pumping speed: 60L/min
Filling speed: 800g/min
Recovery rate: 150g/min
Working tank volume: 12L
External hose: 2.0M
Refrigerant electronic weighing range: 60Kg
Refrigerant electronic weighing accuracy: + 10g
Temperature: 0 -40 degree, relative humidity: 85%
External magnetic field strength: 400mA/m
Power supply: AC220 + 10% frequency: 50/60HZ
Package size: 620X680X1160mm
Machine weight: 90 kg.
The electrical components for the start and operation of a refrigerant compressor are clearly visibly arranged in a transparent showcase and already wired. The capacitor and start-up relay required for the motor are examined. Identifying electrical faults in refrigeration systems requires comprehensive knowledge this knowledge includes the design and operation of the individual electrical components as well as the reading of circuit diagrams. It helps to acquire this knowledge. The simulation of 15 different faults, e.g. coil fracture in the motor, short circuit in the operating capacitor or welded contacts in the start-up relay, is possible. Typical protection devices, such as circuit breaker and automatic fuse, are also arranged clearly visible.
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The unit is similar to the being a bench top mounted unit, and with a mimic of the refrigeration circuit on the front panel. The circuits are arranged within the evaporators to allow for hot gas defrosting. Faults that can be simulated include blockage of pipes, filters, failure of expansion devices, thermostats etc. However the circuit is considerably more complicated including one chamber for chilling and one chamber for frozen produce.
Experimental Capability:
Commercial Refrigeration Trainer principle is similar to the but covers a range of refrigeration faults.
It also covers a range of refrigeration faults include fault on the compressor, fault on the oil separator, fault on the constant pressure regulator, fault initiated by blocked freezer evaporator or liquid line or by restricted freezer liquid line or by blocked drier or by blocked condenser air path or by compressor short cycling, faulty check valve, fault on freezer TEV, refrigerator TEV etc.
The refrigeration trainer can be used as an introduction to the basics of refrigeration circuits including safety & operating switches conveniently built into the electrical circuits with the student assessing the consequences, & building up a diagnosis capability.
Features of Commercial Refrigeration Trainer:
Expansion of refrigerant is possible through a number of different devices such as a regulating valves & capillary tubes of various lengths. Pressure is displayed at two points on the circuit
Faults are cleared by releasing the depressed switches & by opening the hand valves. Adjustment faults may be introduced by setting incorrect values on the Pressure stats on the front panel.
The refrigeration trainer provides additional refrigerant capability, with both chiller & freezer chamber. A defrosting heater is provided driven by hot refrigerant gas. Fault initiation is also included
The training system provides functioning refrigeration circuits utilizing commercial control & components. It provides realistic training in setting up, operating & fault finding in refrigeration systems. The system operates with one of the latest environmentally acceptable refrigerants
A mimic of the refrigerant circuit is provided on the front panel showing the circuit comprising of compressor, condenser & evaporator with an insulated chamber.
The refrigeration trainer is mounted on a wheeled stand due to its weight but at bench top height to provide students with experience in the safety, operation & faults of a refrigeration system
Faults can be initiated by switches set in the control & monitoring circuits
Faults that can be simulated include blockage of pipes filter, failure of expansion devices, thermostats etc Faults are selected by depressing switches & by use of the hand valves.
The test rig comprises of a refrigerating chamber with forced draught evaporator fed by a thermostatic expansion valve, a condensation unit of 250 W; transparent access panel; refrigeration circuit with flow display screen equipped with heat exchanger for subcooling the liquid and the solenoid valve; electric defrost system and control through programmable PLC and timing. Our equipment allows students to visualize and study the process of industrial refrigeration. Despite being a bench top unit, it includes all the essential components of a large scale installation. The unit has been built using modular systems and it can reach a cooling temperature of -30ºC. It includes a drying filter and a liquid storage tank.
Experimental Capability:
Heat transfer and thermal insulation
Coolants
Calculation of thermal loads
Refrigerating chambers and industrial refrigeration
Automatic control and instrumentation
Psychrometric processes (low temperature)
Refrigerator cycles
Steam compression
The fault switches are hidden beneath a panel on the door of the control cubicle so they are not visible whilst the particular fault is being diagnosed. This allows the unit to be demonstrated in the classroom, which in the real world may not be possible. The cubicle is fitted with examples of the typical devices one may come across in the field, such as high and low pressure switches and a thermostat. The allows the lecturer to introduce 12 faults into a control circuit, which has been wired by the student. The Unit has a mimic diagram on the front panel, which simulates an actual compressor control circuit.
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Standard Refrigeration System Training Device can be used to train students to master the theoretical knowledge and practice skills of the standard refrigeration system.
Structure And Compositions:
Evaporator: tube air-cooled type, transparent chamber, and damper
Compressor: 1/2HP, single phase 220V, control box
Condenser: Air-cooled type, single phase 220V, include transparent glass tube
Accumulator: 1/2HP, transparent glass type
Filter dryer: 3/8 nut clamp type or welding type
Sight glass: Welding type or nut clamp type
Manometer: High pressure, low pressure
Expansion valve: manual expansion valve
Electronic valve: 3/8 nut clamp type or welding type.
For better process monitoring the evaporator and condenser are of transparent design evaporator and condenser with pipe coil
Temperature sensor, power meter, manometer in the refrigeration circuit, flow meter for hot and cold water and refrigerant
Demonstration of the processes in a refrigeration circuit
Safety valves at the evaporator and condenser
Expansion valve in the shape of a float valve
Pressure switch to protect the compressor.
Instruments are provided for measurement of temperatures, pressures and cooling water flow rates. The Refrigeration Trainer system requires outside water supply. A table top Refrigeration Trainer system is used to investigate energy balance at compressor, condenser and evaporator. Both the condenser and evaporator used water cooled heat exchangers.
Experiments:
Overall heat transfer coefficients for evaporator and condenser.
Familiarization with refrigeration cycle and components.
Effects of load variation.
Energy balances at evaporator and condenser.
