This paper discusses an experimental investigation on nucleate pool boiling of distilled water from electrically heated two horizontal reentrant cavity (REC) copper tubes arranged in a vertical row at atmospheric and sub-atmospheric pressures. The tubes are heated individually as well as simultaneously with same and different values of heat flux. Heat flux ranges from 18.886 to 44.744 kW/m~2, and the pressure from 35.36 to 97.5 kPa. Data analysis yields heat transfer coefficient of upper tube to be higher than that of lower tube. The functional relationship between heat transfer coefficient and heat flux for upper tube is found to be different than that of lower tube, indicating a substantial influence of lower tube vapour bubbles on upper tube. Further, an equation is developed to determine heat transfer coefficient of upper tube as a function of heat flux of lower and upper tubes.
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