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Industrial refrigeration:
How does an industrial refrigeration system work?
Why it is important to use a backpressure valve ?
Case 1: Stopping of the refrigeration system
Case 2: Starting of the refrigeration system
Case 3. Safety devices in an industrial refrigeration system
Oil pressure sensor:
Electric heater for defrosting
Routine maintenance in an industrial refrigeration system:

Industrial refrigeration systems are heavily used in supermarkets, airports and provision stores for storing a variety of foods, vegetables, and frozen products using multiple ev***rators set at different temperatures.

Large refrigeration compressors usually consist of 2 to 4 cylinder units to handle large refrigeration plants.

Only some compressor cylinder units are provided with unloaders so that refrigeration capacity can get adjusted as the food stock starts becoming cold.

The commercial refrigeration system consists of thermostats, solenoid valve, a thermostatic expansion valve (TXV or TEV) or metering valve and back pressure valve with safety devices such as LP cut out, HP cut out, L**e oil cut out and compressor unit unloader.

Large industrial refrigeration plants have a commercial freezer and Meat room with the temperature maintained at -20°C or -24.8°F and -15°C or 5°F, hence temperature is sensed by thermostats.

Where’s Vegetable room thermostat set at +5°C or 41°F.

A thermostat has two functions one is to immediately stop the cooling of refrigerated room, and another one is to start the cooling operation of less cooled refrigerated room.

All is done by operating the solenoid valve to close and open the flow of refrigerant to the refrigerated room.

Solenoid valves are controlled by the thermostats attached at each refrigerated rooms.

Commercial Freezer room
Meat room
Vegetable room
How does an industrial refrigeration system work?
Generally, for commercial freezer room and meat room the thermostat differential temperature setting is set at around 5°C.

Which means, the solenoid valve opens and starts to increase cooling for the freezer room when its temperature drops to -15°C (ie 5°C drop in temperature).

The same goes for the meat room at -10°C.

Similarly, the solenoid valve opens for the vegetable room at (7°C).

The thermostatic expansion valve(TEV or TXV) adjusts the degree of superheat; so that ev***rator may not starve of refrigerant.

Why it is important to use a backpressure valve ?
A back pressure valve fitted at the ev***rator outlet for the vegetable room since vegetables are sensitive to excessive change in temperature, which could damage these perishable food items.

Therefore, a positive temperature is maintained in the vegetable room to keep the vegetables fresh and undamaged.

The back pressure regulator valve keeps the rate of ev***ration reduced to provide a gradual cooling.

It also creates back pressure on the ev***rator coil, to ensures that most of the liquid refrigerant is made available at lower temperature zones ie. freezer and meat room.

Back pressure valves are spring loaded and a non-return valve.

Case 1: Stopping of the refrigeration system
Now, let’s consider the meat room achieves its temperature of -15°C then the solenoid valve to this room closes which leads to a drop in suction pressure at the compressor.

Drop in suction pressure activates the unloader to unloads one of the compressor units and keeps the unit cut off by lifting its suction valve open.

Thereby reducing the compressor capacity and not allowing the compressor motor to stop on a low-pressure trip.

Industrial Refrigeration System: illustrated Helpful Guide - refconhvac.com Working of commercial refrigeration in supermarkets,storing variety of food products,controlled byTEV or TXV,ev***rator etc ,safety devices and maintenance

Refrigeration System Problems and Solutions:
1. Room temperature warm
2. Compressor suction pressure high
3. Compressor suction pressure low
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4. Compressor discharge pressure high
Causes for discharge high pressure:
5. Abnormal noise heard during operation
6. Compressor low oil pressure
The following would cause low l**e oil pressure:
Chocked oil filter
Oil separator blockage preventing oil return to the compressor
Carryover of oil into the refrigeration system.
Bearing wear within the compressor.
7. Excess compressor overload
Possible cause includes:
8. Refrigerant low on charge and overcharge indications and remedies
Undercharge symptoms:
Solution:
Overcharge symptoms:
Symptoms are:
Solution:
9. Moisture in the refrigeration system, problems, and remedy
Remedy:
10. Short cycling of refrigeration compressor
Reasons for above:
What is compressor anti-recycling?
11. Frosting at the suction of the compressor
Reasons:
12. What happens if air enters into the refrigeration system and how to remove it?
Indication for air ingress
Reason:
Remedy:

1. Room temperature warm

Lack of refrigerant present in the system.
Blocked filter at the drier or expansion valve.
Ev***rator inlet solenoid closed.
Condenser fan motor issue, less heat transfer available for a given mass of refrigerant.
Defrosting element still operational.
Compressor capacity control faulty leading to less coolant effect across the thermostatic expansion valve.

2. Compressor suction pressure high

Fractured compressor valves, causing the compressor capacity to fall.
Ev***rator load too high, caused by room items recently changed entry door left open.
Excess refrigerant charge. This fault is combined with a low compressor superheat and indicates liquid in the suction line. The solenoid valve should be closed quickly to prevent liquid damage to the compressor.
Expansion valve stuck in a fully open position, caused by dirt in the expansion valve.

3. Compressor suction pressure low

Blocked filter or closed valve in the system. In this mode, the compressor is extracting more from the ev***rator than the expansion valve is supplying leading to low suction pressure and possibly compressor to short cycle.

Refrigerant charge too low. There is not enough refrigerant within the system to allow the compressor to operate at the present capacity setting. Increased compressor run time.
The liquid refrigerant flow may be disturbed: Fully open the valves in the liquid refrigerant line if not fully open. Confirm line filters not chocked.

Thermostatic expansion valve clogged with ice or oil dust mixture: Dissemble expansion valve (TEV) and clean the ice with dry compressed air. Activate the desiccant of drier filter by the heater. Take off oil mixture dirt.

Less opening for the expansion valve or superheat very low: Adjust the expansion valve opening and ensure temperature sensor attached properly to the ev***rator outlet.
Ev***rator cooling capacity lowered by dust and frost: Check fan operation working normal. Remove dust by soft brush and carry out defrosting.

Refrigeration System Troubleshooting: A Practical guide - Refcon hvac refrigeration problem,solution,causes due to air,moisture,short cycling,anti cycling,warm room,low charge,over charge refrigerant, overload,pressure high,low

Factors affecting an air conditioning system.
1. Relative humidity
2. Dew Point
3. Specific humidity
4. Dry bulb temperature
5. Wet bulb temperature
6. What is a Comfort zone in Air Conditioning System?
Five Major Dry Air Problems From Air conditioner | AC On our Body
Effect of Legionella bacteria in Air Conditioning Systems
8. Commercial ducted air conditioning systems
8a. Single Ducted Air conditioning System
8b. Dual Ducted Air conditioning System
9. Role of Psychrometric Charts in AC systems
9a. Warm climate
9b. Cold climate

The atmosphere contains a number of water particles in suspension from the ev***ration of water at sea, lakes, ponds, etc. which takes place at all temperature. The amount of water particles held in suspension varies but is limited by the capacity of the air itself.

At any given temperature the air can only hold a certain amount of water particles at which point it is said to be saturated, any reduction in temperature will then cause excess v***r to be condensed back into the water leading to Rain.

Air conditioning is vital to the comfort for those living in higher humid areas.

Effects of dry air:

1. Eyes become dry.
2. Skin dryness.
3. Itching and scratching of the skin.
4. Nose bleeding.
5. Legionella

How to Install an AHU: 9 Factors to Consider - Refcon hvac This article covers the 9 factors you need to consider before installing an AHU, such as location, size, noise, efficiency,diseases and maintenance.