Comparison of flow boiling characteristics between minichannel and macrochannel in solar still-numerical study

ABSTRACTThe thermal performance of a rectangular minichannel has been estimated for various heat fluxes (1 kW/m2 to 2 kW/m2) and fluid mass flux rates (20 g/s to 40 g/s). The mixture model is used to determine two-phase flow characteristics in the mini-macro channel. The focus of the present work is to establish prime factors for the enhancement of vapour fractions inside the minichannel (< 3 mm) and macrochannel (> 3 mm). The fluid flow characteristics are explained with help of temperature difference (the wall side and water film side), friction factor, Nusselt number, evaporative thin film thickness, heat transfer coefficient and vapour fraction. Validation of current simulation with earlier research article shows good agreement. The friction factor value for the minichannel and macrochannel are 0.0004 and 0.0011, respectively. It is found that heat transfer is significantly more in macrochannel pipes compared with minichannels. By using the dimensional analysis, empirical correlation is developed for vapour fraction with dependent parameters such as channel diameter, fluid mass flow rate and heat flux the first time. The predicted correlation of vapour fraction and film thickness help to understand the pronounced effect of channel diameter on heat transfer.DisclaimerAs a service to authors and researchers we are providing this version of an accepted manuscript (AM). Copyediting, typesetting, and review of the resulting proofs will be undertaken on this manuscript before final publication of the Version of Record (VoR). During production and pre-press, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal relate to these versions also. Additional informationNotes on contributorsThavamani Jayaraj Thavamani Jeyaraj is an Assistant Professor at the Department of Mechanical Engineering, SRM Institute of Science and Technology, Kattankulathur, Chennai, Tamilnadu. India. He obtained his Master of Engineering in Refrigeration and Air conditioning from Anna University in 2009. He is doing Doctorate in the area of influence parameter of solar distillation system. For the past 13 years he has been working in the heat transfer and refrigeration system field.Pankaj Kumar Pankaj Kumar is a Research Assistant Professor at the Department of Mechanical Engineering, SRM Institute of Science and Technology, Kattankulathur, Chennai, Tamilnadu. India. He has been working in the field of two-phase flow and heat transfer for the past 10 years. He has published more than 16 research papers in international journals focusing on cavitation, two phase flow, and flow past a circular cylinder.