compressors
air conditioning compressors and other components.
The air conditioning compressor is Part of a split system heat pump or air conditioner’s outdoor unit, since it produces heat, that controls the pressure applied to the refrigerant. This is necessary for taking heat to warm your home or getting rid of heat to keep your home cool.
The purpose of the compressor in the vapour compression cycle is to accept the low-pressure dry gas from the evaporator and raise its pressure to that of the condenser. Compressors may be of the positive displacement or dynamic type. The general form of positive displacement compressor is the piston type, being adaptable in size, number of cylinders, speed and method of drive. It works on the two-stroke cycle. As the piston descends on the suction stroke, the internal pressure falls until it is lower than that in the suction inlet pipe, and the suction valve opens to admit gas from the evaporator. At the bottom of the stroke, this valve closes again and the compression stroke begins. When the cylinder pressure is higher than that in the discharge pipe, the discharge valve opens and the compressed gas passes to the condenser. Clearance gas left at the top of the stroke must re-expand before a fresh charge can enter the cylinder.
The first commercial piston compressors were built in the middle of the last century, and evolved from the steam engines which provided the prime mover. Construction at first was double acting, but there was difficulty in maintaining gas-tightness at the piston rod, so the design evolved further into a single-acting machine with the crankcase at suction inlet pressure, leaving only the rotating shaft as a possible source of leakage, and this was sealed with a packed gland.