the experimental study of the heat transfer using an ionic liquid as in a micro heat exchanger

Ionic liquids are an effective candidate for heat transfer fluid due to their low vapor pressure, high thermal conductivity, low melting point, high thermal stability# in this experimental study, the heat transfer performance of 1-hexyl-3-methylimidazolium tetra fluoroborate (hmim bf4) as an ionic liquid has been compared with a lake salt (prepared from lake of urmia) as well as tap water in a micro scale double tube heat exchanger# these three fluids were used as the operating fluid in the tube side and the tap water was employed in the shell side in a counter-current arrangement# heat transfer was performed in a micro-heat exchanger with a length of 50 cm, the tube diameter of 0#91 mm and the shell diameter of 6 mm# the volume flow rate of the tube side fluid was changed in the range of 0#5 to 3#3(ml/min) at two inlet temperatures of 60 and 70 °c# it was observed that the overall heat transfer coefficient of the micro- heat exchanger will increase as the volume flow rate of the tube side fluid increases# furthermore, the overall heat transfer coefficient in the case of 70 °c for the inlet temperature is 19#2 % higher than its value for the other one (60 °c)# the experimental results show that the overall heat transfer coefficient of the micro-heat exchanger using hmim bf4 is 58 and 80% higher than its value for the case of the lake salt solution and water as the working fluids in the tube side