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ABSTRACT

The condenser and evaporator are important components of the vapor compression refrigeration (VCR) system along with the expansion valve and the compressor. Any change/modification in the design of the heat exchangers can affect the dynamic behavior of the VCR system. In this context, this paper aims to analyze the dynamic performance of the VCR system under different geometrical parameters such as the external tube diameter, the tube pattern and the baffle plate orientation of the shell and tube type condenser, while maintaining a fixed evaporator geometry. A disturbance is considered to be applied in the chilled water inlet temperature in step increments of 5 °C (41 °F) from the initial steady state. It is observed that a tube with a larger external diameter results in improved performance due to increased heat transfer surface area. A tube pattern of 60° rotation and a horizontal baffle cut enable enhancement in performance from the initial steady-state until the new steady state is reached. This is credited to an improved crossflow stream in both cases which causes more fluid contact with the tube and improved mixing of the fluid. Overall, it is concluded that a larger external tube diameter, a 60° tube pattern and a horizontal baffle cut facilitate good chiller performance. Furthermore, the transition durations of the evaporator capacity with the respective configurations are 14.5s, 15s, and 13s, respectively compared to the base case i.e. 12.5 s.