A. INTRODUCTION

Although much of the thermodynamic modeling and analysis in this book relates to cooling systems effectively as blackboxes that must be characterized strictly from external non-intrusive measurements, it is important to have some appreciation of the contents of those blackboxes. What are their principal components? What types of thermodynamic cycles are involved? What are the fundamental limits on chiller or heat pump performance? What are the main irreversibilities? Where do these irreversibilities enter and how do they impact thermodynamic performance? Of what practical aspects of specific chiller components should the reader be aware prior to entering the realm of thermodynamic modeling? These are the issues we will try to address succinctly in this chapter.

The chapter divides primarily into the two most general categories of cooling devices: work-driven (mechanical) and heat-driven (absorption). At the end of the chapter we will also look at two non-conventional chillers, based on the thermoacoustic and thermoelectric effects.

We move from the general to the specific. First, we review the derivation of fundamental upper bounds for thermodynamic performance, with little regard to the particulars of the machine. The results are essentially device-independent. One would imagine that in designing real cooling systems, the properties of these idealized maximum-performance machines should be imitated to the greatest extent possible. The degree to which this can be accomplished is discussed, along with examples of the cooling cycles that have evolved as the preferences...