What is one main reason reciprocating compressors are not fully efficient?

Reciprocating compressors experience inefficiencies primarily due to clearance volume, which is the space in the cylinder that is not filled with refrigerant during the compression cycle. This volume is essentially the residual space left over in the cylinder when the piston moves to the top, meaning that a portion of the cylinder does not participate in the compression of the refrigerant vapor.

When the piston compresses the refrigerant, it compresses not just the vapor from the evaporator but also the leftover vapor in the clearance volume from the previous cycle. This leads to a situation where some of the energy used during compression is effectively wasted, as it is not being utilized to compress the refrigerant from the evaporator fully. Consequently, this reduces the overall efficiency of the compressor.

By minimizing the clearance volume through design and operational adjustments, efficiency can be enhanced. Understanding this concept is crucial for optimizing the performance of reciprocating compressors in commercial refrigeration systems.