Refrigeration system?

                                                                     GAS FILTER                                                                      

Gas filters are generally made of very fine wire gauze surrounded by a metallic body. These are found in various designs and used in different parts of the refrigeration system, such as in the liquid line, suction port of the compressor, and inlet of an expansion valve. 

The function of the filter is only to purify the refrigerant and checking the carbon particles to flow in the system. Such type of filters are also known as strainers. 

  How to refill air-condition refrigerant R22 -Hindi  

                                                         DRIER OR DEHYDRATOR                                                       

Dehydrator is used for removing the moisture from the refrigeration system. Usually dehydrator consists of a cylinderical shell charged with some moisture absorbing chemical and connected in the liquid line. The chemical used may be calcium oxide, calcium chloride, silica gel, activated alumina, drierite (calcium sulphate), bead silica gel, and other dehydrating mediums. A dehydrator charged with a dehydrating medium should not be opened in the atmosphere. 

 In construction, it is made of brass or steel in the shape of a cylindrical shell. The shell has a strainer charged with a dehydrating medium. The suitable connectors are made at the two ends of the shell for flare fittings. These are generally located in the liquid line just after the condenser or receiver in the direction as shown by an arrow. Its size depends upon the size of the unit with which it is to be used. Manufacturers themselves specify the capacity of a dehydrator. 

There are two types of dehydrators :—(a) Sealed type, (b) Refillable type. 

(a) Sealed type, (b) Refillable type. 

Q. What is a drier ?

Ans. A device designed to remove moisture from the refrigeration system is called drier. 

Q. For what purpose a drier is used ?

Ans. 

1. It checks the carbon particles to flow further in the system. 
2. It removes moisture from the refrigerating machine. 
          

                                         THERMOSTATIC EXPANSION VALVE                                                 

The thermostatic expansion valve differs from the automatic expansion valve that the action of automatic expansion valve is controlled by increase or decrease of pressure in the low side of the system while the working of the thermostatic extansion valve depends upon the decrease or increase of temperature of the suction line.

 Construction : It has a brass body with two passages for the inlet and outlet of the liquid refrigerant. The orifice or the seat of the expansion valve is covered by a needle installed in it. The needle is connected to flexible metal bellows by a rod. In addition to it, it has a thermostatic element charged with a volatile substance (usually the same refrigerant which is used in the refrigerating machine, with which the valve is fitted). In other words it is similar to automatic expansion valve except that it has a thermostatic element, that is a bellow, capillary tube and a thermal bulb charged with some volatile liquid. 

Installation : The valve is installed in the liquid line just before the evaporator in the direction of arrow on it. The bellow may be fitted in any position but the thermal bulb must be fitted tightly with the suction line where it leaves the evaporator.  

A Thermostatic Expansion Valve 

 Its working depends upon the difference of temperature of suction line. Thus a rise in evaporator temperature will increase the temperature of the suction line and the thermal bulb of the expansion valve. The higher temperature produces higher . pressure within the bulb, capillary and bellow which causes the metal bellows to expand and force the needle to be away from its seat. Thus it permits more liquid to enter into the evaporator to take care of the increased heat load. Then a fall of evaporator temperature will decrease the temperature of the suction line and thermal bulb. This reduces the pressure of the gas inside the bulb, which causes the bellow to contract-Thus the needle comes closer to its seat or orifice and admits less refrigerant to evaporator. 

 Interior view of a thermostatic expansion valve 

 Adjustment : All the valves are factory. adjusted for a suitable pressure. So, there is no need of altering the adjustment. In the case, when the amount of refrigerant injected