Diagnostics and optimization of reciprocating chillers: theory and experiment

We develop a simple analytic diagnostic model for reciprocating chillers. With only a handful of non-intrusive, in situ measurements, one can then ascertain quantitatively how chiller performance changes with time or after a prescribed modification. We derive how reciprocating chillers can be characterized by just three parameters with clear physical significance. We then verify the correspondence between theory and reality with detailed experimental measurements. It is also demonstrated how this model can be used to establish optimal operating conditions for reciprocating chillers, and to evaluate potential improvements that stem from changes in operating conditions or the distribution of heat exchanger inventory. Again, comparisons with actual performance data from commercial chillers are provided. We give quantitative expression to the contribution to chiller efficiency of internal dissipation from compression and throttling, and consequently reinforce the fact that endoreversible chiller models are far off the mark.