Ammonia evaporation in a mixed configuration chevron plate heat exchanger with and without miscible oil Tariq S. Khan a , Mohammad S. Khan b,* , Ming-C. Chyu c , Zahid H. Ayub d a Department of Mechanical Engineering, Petroleum Institute, United Arab Emirates b Department of Mechanical Engineering, Mohammad Ali Jinnah University, Islamabad, Pakistan c Department of Mechanical Engineering, Texas Tech University, USA d ISOTHERM, Inc., Texas, USA article info Article history: Received 26 May 2014 Received in revised form 28 November 2014 Accepted 3 December 2014 Available online 11 December 2014 Keywords: Plate heat exchanger Ammonia Evaporation Miscible oil Heat transfer Pressure drop abstract An experimental study was conducted to determine the effects of miscible lubricant oil on evaporation of ammonia in a vertical chevron plate heat exchanger. The heat exchanger was configured in a U-type counter flow arrangement with mixed (30  /60  ) chevron plate configuration. Experiments were carried out for four saturation temperatures ranging from 25  C to 2  C for a fixed ammonia mass flux rate of 6.5 kg m 2 s 1 and over a range of heat flux levels resulting in a vapor quality at the heat exchanger exit ranging between 0.5 and 0.9. For a given saturation temperature, experiments were performed for 0%, 3%, 6% and 9% oil concentrations, by volume in ammonia. The oil concentration, exit vapor quality, heat flux and saturation temperature were found to have significant effects on the heat transfer coefficient and pressure drop of ammonia. Based on the experimental data, correlations to estimate two phase Nusselt number and friction factor, generalized for the whole range of oil concentration have been presented. © 2014 Elsevier Ltd and IIR. All rights reserved. Evaporation d'ammoniac dans un  echangeur  a plaques  a chevrons avec et sans huile miscible Mots cl es : Echangeur de chaleur  a plaques ; Ammoniac ; Evaporation ; Huile miscible ; Transfert de chaleur ; Chute de pression * Corresponding author. Tel.: þ92 51 111878787; fax: þ92 51 4486705. E-mail address: mskhan@jinnah.edu.pk (M.S. Khan). www.iifiir.org Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/ijrefrig international journal of refrigeration 51 (2015) 120 e134 http://dx.doi.org/10.1016/j.ijrefrig.2014.12.002 0140-7007/© 2014 Elsevier Ltd and IIR. All rights reserved.