Shell side direct expansion evaporation of ammonia on a 3-D structured surface tube bundle with exit superheat effect

摘要: There is no data available on direct expansion evaporation of refrigerant on the outside of an enhanced surface tube bundle. This study is in continuation of the previous similar study conducted on a plain tube bundle. With the current Ozone Depletion and Global Warming issues it is critical to develop systems with low charge refrigerants especially with natural refrigerants such as ammonia which has zero Ozone Depletion Potential (ODP) and zero Global Warming Potential (GWP). This study presents results of an experimental work on direct expansion of ammonia on a triangular pitch 3-D structured enhanced surface tube bundle with saturation temperature range -2 to -20 °C, heat flux range 15 to 48 kW m−2 and exit superheat range 2 to 10 °C. The test matrix falls well within the practical operating conditions of industrial refrigeration systems. A classic increase in heat transfer coefficient is observed with …