Experimental study on thermal characteristics of ammonia flow boiling in a plate evaporator at low mass flux

• Ammonia flow boiling at low mass flux in a plate evaporator is investigated.
• Heat transfer coefficient as a function of quality is presented.
• Effects of mass flux, heat flux, channel height, and saturation pressure are discussed.
• Empirical correlations are developed by using Lockhart-Martinelli parameter.

Thermal characteristics of a plate evaporator using ammonia are experimentally investigated. The effects of mass flux, heat flux, channel height, and saturation pressure on heat transfer coefficient of the evaporator are discussed. The experiments are conducted for mass flux (5 and 7.5 kg m−2 s−1), heat flux (10, 15, and 20 kW m−2), channel height (1, 2, and 5 mm), and saturation pressure (0.7 and 0.9 MPa). Heat transfer coefficient is obtained as a function of quality for all experimental conditions. The characteristics of heat transfer coefficient are discussed and compared with those of earlier works. All experimental results are compiled by using Lockhart–Martinelli parameter. The developed empirical correlation predicts 85% of the experimental data within ±30% range.