Abstract:
In order to design and select the air conditioning unit, the energy saving regulation from ministry of
energy must be applied since the year 2009 in Thailand. The regulation specifies the minimum
performance of air conditioning unit in terms of coefficient of performance, energy efficiency ratio, and
kilowatt power consumption per ton of refrigeration. The regulation was adopted the oversea standard
which utilize the condition according to specific environment. However, the installation in Thailand ambient
condition and also improper installation may deviate from the working condition of air conditioning unit.
This may degrade system performance. This research work aims to investigate the influence of
environmental factor comprising of ambient temperature and evaporating superheat. Results show that,
when the increment of ambient temperature causes the condensing temperature rise up from 50 to 55
deg C, the system efficiency will drop down 14%. When the evaporating pressure decreases from 89 to
70 psia, the system efficiency will drop down 19%. Significantly, the decrement of evaporating
temperature causes the extreme superheat temperature at the compressor discharge. The experiment
was set up to verify the mathematical model in this research work. Pressure and temperature sensors
were installed in 12,000 Btu/hr split type air conditioning unit. The ambient condition of condensing unit
was controlled. The model was verified by experiment at design condition. The test results were in a good
agreement.