A general evaluation of the performance of a Vuilleumier
heat pump for residential heating is given. The basic
considerations were devoted to the choice of hot,
intermediate and cold operating volumes and temperatures,
to the phase angle of the two displacers, to the dead
volumes and to the choice of the working gas. Specific
attention was then paid to the heat transfer problems at
each of the three temperatures.
The main difficulty was identified with the solid-gas
heat transfer at both low and intermediate temperatures.
For a machine of gas volume 5,2 dm3, pressure 150 bar,
operating frequency 1/s and heat rejecting capacity 10
kW, the temperature drops were evaluated to be 105 K over
the hot end heat exchanger, 40 K over the intermediate
temperature heat exchanger, and 47 K over the cold end
heat exchanger. This limits the coefficient of
performance defined as the ratio of the heat rejected at
the intermediate temperature to the heat supplied at the
high temperature to 1,9. This figure is lower still when
other loss factors are taken into account. Moreover, the
pressure level should necessarily be dropped in order to
comply with the regulations for unauthorized users.
Another sample calculation for 16 bar gas pressure, 3,3
dm3 gas volume, and 16 1/s operating frequency yielded
only 1,3 for the coefficient of performance.
|Place of Publication||Espoo|
|Publisher||VTT Technical Research Centre of Finland|
|Number of pages||37|
|Publication status||Published - 1981|
|MoE publication type||D4 Published development or research report or study|
|Series||Valtion teknillinen tutkimuskeskus. Tutkimuksia - Research Reports|
- heat pumps