الفهرس 
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Abstract
Thesis subject: studying the characteristics of heat pipe heat
exchangers in air conditioning systems
In this thesis a study has been made on a heat pipe heat exchanger used
in heat recovery. The test rig has been built to simulate the same
conditions of the heat recovery systems in air conditioning
applications. In these systems, the heat pipe-heat exchanger is
considered one of the best solutions especially in hospitals and
laboratories in which zero cross contamination is required.
The measured data acquired from the test rig were analyzed to evaluate
the thermal behavior and effectiveness of the heat exchanger.
Cold and hot air ducts have been connected to a heat pipe heat
exchanger. The first two experiments have been carried out by
changing the hot air inlet temperature from 32 ~ 55 °C.
The inlet cold air temperatures has been maintained constant at 26 °C
in one experiment and 28 °C in the other one.
Another three experiments have been carried out, by changing the ratio
of the air mass flow rates between the cold and the hot air from 1 to
almost 2, whilst the temperature of the cold air remained constant at 26
°C. Also the hot air temperature is maintained constant at either 35 °C,
40 °C and 45 °C. Hence for each experiment the thermal performance
and effectiveness of the heat recovery system were investigated.
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The results indicate that when the hot (fresh) air temperature increases,
the temperature difference of the hot and cold air streams increase.
The effectiveness of the evaporator was increased up to almost 39 %
due to increasing the hot air temperature to 55 °C.
The effectiveness of the heat pipe evaporator section was subjected to
a positive effect with changing the mass flow ratios. It is also found
that the fresh (hot) air temperature has a great effect on enhancing the
heat transfer performance of evaporator part of heat pipes heat
exchanger.
Key words:
Heat pipe, Heat exchanger, Heat recovery, Air conditioning