Article ID Journal Published Year Pages File Type
789392 International Journal of Refrigeration 2014 11 Pages PDF
Abstract

•Experimental study for heat transfer & pressure drop data in mixed PHE using NH3.•Saturation temperature & heat flux varied from −25 to −2 °C and 21 to 44 kW m−2.•Empirical correlations developed for two-phase Nusselt number and friction factor.•Present data compared with the available evaporation data of ammonia.•A generalized Nusselt number correlation is also proposed.

Ammonia is a naturally occurring environment friendly refrigerant with attractive thermo-physical properties. Experimental investigation of heat transfer and pressure drop during steady state evaporation of ammonia in a commercial plate heat exchanger has been carried out for an un-symmetric 30°/60° chevron plate configuration. Experiments were conducted for saturation temperatures ranging from −25 °C to −2 °C. The heat flux was varied between 21 kW m−2 and 44 kW m−2. Experimental results show significant effect of saturation temperature, heat flux and exit vapor quality on heat transfer coefficient and pressure drop. Current mixed plate configuration data are compared with previous studies on the same heat exchanger with symmetric plate configurations. This comparison highlighted importance of optimization in selection of the heat exchangers. Correlations for two phase Nusselt number and friction factor for each chevron plate configuration considered are developed. A Nusselt number correlation generalized for a range of chevron angles is also proposed.

Related Topics
Physical Sciences and Engineering Engineering Mechanical Engineering
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