Page 33 - Low Temperature Energy Systems with Applications of Renewable Energy

22 Low-Temperature Energy Systems with Applications of Renewable Energy

Fig. 1.16 Heat-driven absorption refrigerator, modified from Ref. [18].

for convenience, then electricity must be available. The working fluid circulates under
gravity owing to density differences. There are no moving parts and no seals. It is also
silent in operation which can be a desirable feature for certain stealthy situations such
as in military operations. The last gas-fired refrigerator was manufactured in the US in
1957. The product was banned in 1999 after several deaths caused not by ammonia
leakage but by carbon monoxide from faulty combustion of the gas burner. Apparently
the refrigeration system itself was still robust and still sealed after decades of use.
One of the writers (RDP) grew up in a home with such a device; it was a puzzle to
me as a youngster how it could achieve cold from heat, perhaps spurring my interest in
thermal science and engineering.

1.5.6 Exergy assessment of heat pumps

The previous sections considered the performance on the basis of energy. Now the
concept of exergy will be applied to heat pumps. The concept of exergy is based on