الفهرس 
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Abstract
An Experimental apparatus is designed and constructed in the present investigation to study the effect of vibrations on automotive air conditioning system by measuring the heat transfer coefficient during boiling of refrigerant R-134a in the evaporator.The measurements include the effect of heat flux and mass flux on the boiling heat transfer coefficient at different frequencies and amplitudes similar to that occurring in vehicle. The refrigeration cycle and vibration device used in the experimental work consists of a compressor, condenser, expansion valve, motors, plates, springs and a test section that simulates the evaporator. The test section is a shell and tube heat exchanger made from copper tubes. The test section is provided with 6 digital thermocouples distributed along the test section to measure the outside wall temperatures of the refrigeration tube, in addition to two thermocouples used to measure the inlet and exit temperatures of the hot water passing through the test section.
Experimental runs were carried out for heat flux ranged from 20 to 230 kW/m2, mass flux ranged from 102 to 207 kg/m2s, and frequency ranged from 0 to 34.5Hz corresponding to amplitude ranged from 0 to 13.6 mm. The measurements show that at the working pressure and the heat flux, as the frequency of the heating surface increases, the average heat transfer coefficient decreases for all values of mass flux studies.
Also, the average heat transfer coefficient for different values of the heat flux at constant mass flux, were represented as a function of the frequency .It is seen that the average heat transfer coefficient, for the same value of heat flux, decreases as the frequency increases.
The average heat transfer coefficient for different values of the heat flux at constant frequency, were represented as a function of the mass flux .It is seen that the average heat transfer coefficient, for the same value of heat flux, increases as the mass flux increases.
It was indicated from the measurements that, the depression in theaverage heat transfer coefficient increases as the heat flux increases.
Also, the heat transfer coefficient, at constant amplitude, in the tested range increases with the increase of heat flux. Also the average heat transfer coefficient decreases with the increase of amplitude.
A mathematical correlation equation is deduced to relate the heat transfer coefficient with frequency, heat and mas fluxes, with a maximum deviation of ± 10 %.