Chapter hvac engineering Fundamentals: Part 1 Introduction

290
Figur
e
9.2
Refrigeration
cycle
on
pressure-enthalpy
diagram
for
refrigerant-12.
Equipment: Part 1
Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com)
Copyright © 2004 The McGraw-Hill Companies. All rights reserved.
Any use is subject to the Terms of Use as given at the website.

---

Equipment: Part 1
291
Figure 9.3
Two-shell absorption refrigeration cycle.
(not shown) are used in the pipelines to help maintain this pressure
gradient. Heat rejection to the condensing water is roughly twice the
refrigeration effect. In addition to the heat supplied to the generator,
the chemical process of absorption creates some heat.
An absorption refrigeration system has a low coefficient of perform-
ance compared to a mechanical refrigeration system. Normally ab-
sorption can be justified economically only when plenty of compara-
tively low-cost or ‘‘waste’’ heat is available. Solar heat has been used,
although in most areas the cost of its collection makes solar energy
too expensive to compete with conventional fuels.