Abstract
Shell and tube heat exchangers are widely used in various industrial refrigeration systems. With recent global warming and ozone depletion concerns it is crucial to develop low charge refrigeration systems with environment friendly natural refrigerants such as ammonia. This paper presents a comparative analysis between a conventional shell and tube flooded evaporator and a low charged direct expansion evaporator with ammonia evaporating on shell side of a triangular pitch plain tube bundle. The saturation temperature was varied between -1.7?C and -20?C with heat flux range of 5 to 45 kW/m2. The degree of superheat for direct expansion case was varied from 2 to 10 K. The heat transfer coefficient was observed to increase with an increase in saturation temperature and heat flux for both flooded and direct expansion case, while for direct expansion case heat transfer coefficient was observed to decrease with an increase in the degree of exit superheat.
Published Version
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