Introduction

Gas charging is one of the vital parts of a chiller to run. There are several processes regarding gas charging in a chiller. However there are several types of refrigerants in the market available, most commonly used in chillers is R135.

Types of chiller

Types of chillers vary and can be classified in several fields. Based on condensed water cooling system chillers are of Two type,

Water cooled chiller
Air cooled chiller

A water cooled chiller cools its condensed water by flowing it through pumps and into cooling towers.

Whereas, an air cooled chiller cools its condensed water by ambient air with built in fans.

Also there are several types regarding the type of compressors.

Reciprocating Compressor
Scroll Compressor
Screw Compressor
Turbocor Compressor

Reciprocating Compressors are too outdated and are not used in big chillers.

Scroll Compressors on the other hand used in split type ac and Packaged Type Chillers.

Most commonly used compressor in large industrial, commercial chillers is Screw type compressor. It is well established and still a highly demanding compressor. We will talk more elaborately about it later.

And another more new addition is Turbocor compressor also known as Magnet bearing compressor. Magnetic bearing compressors are gaining popularity due to its oil free operation. Unlike screw compressors, magnetic bearing compressors do not need any lubricating oil. Because its shaft rotates on the technology called magnetic levitation, and does not come to any mechanical contact with any other parts.

Vacuum Process of a chiller

From the factory a chiller can be shipped filled with a neutral gas such as Nitrogen or can ship with nothing inside. It needs to be confirmed from manufacturer before doing any gas related work. Also the condition of the gas line and liquid line can be determined by measuring the pressure inside the lines. However in most cases the chiller is filled with Nitrogen gas. If measured pressure found positive then vacuum pumps are to be set at the service valve points. There are several service valves in the different areas of a chiller. So more than one vacuum pump can be installed to make the process faster. There is a meter called a micron meter which can measure the humidity inside. Generally the vacuum process is done so that there remains very little humidity in the system. When the humidity comes down to a threshold point the system is ready to charge the refrigerants.

Charging the gas

There are two ways of charging the gas, charging the refrigerant as gas and charging the refrigerant as liquid.

As we know compressors can not handle liquid refrigerants very well, and liquids are harmful for compressors. Hence at the compressor side gas form of refrigerants are charged. To do so, the refrigerant cylinder must stand up words only then the refrigerants will get vaporized and gas form of refrigerants will fill the compressor side ares, and the vapor will spread throughout the system which helps further procedure.

Secondly the liquid form of refrigerants will be charged at the evaporator side right before the expansion valve. This way 2 to 3 cylinders are charged.

Finally it is time to start the machine. When the chiller is started, the refrigeration cycle starts, which creates demands of more refrigerant gas. Then the rest of the refrigerants are charged as liquid.

This is how to charge refrigerants in either an air cooled or water cooled chiller.