is it possible to achieve the outlet temperature of cold stream greater than the outlet temperature of hot stream in a counter current sheel and tube heat exchanger..????
Absolutely. The previous answer is correct for a co-current flow (hotest hot fluid and coldest cold fluid enter the same side of the exchanger). Please try to follow my description below of how to calculate the temperatures for countercurrent flow.. It is hard for me to write this clearly. Lets take hot water entering the tube from the left at 90C and cold water entering the shell from the right (countercurrent) at 40C. Lets say that the hot water in the tube is cooled to 60C. We know that the heat lost by the hot water is Q=m·Cp·(Tout-Tin). We also know that whatever heat the hot water lost, the cold water gained. Lets assume equal flow rates and the Cp is constant. Qhot = mCp(T hot out - T hot in) = mCp(60-90) = -30mCp Qcold = mCp(T cold in - T cold out) = mCp(40-T cold out) Qhot = Qcold (what heat the hot side loses the cold side must gain) -30mCp=mCp(40-T cold out) (m and Cp are the same so cancel out) -30 = 40 - T cold out -70 = - T cold out T cold out = 70. So you can see that the cold side outlet temperature (70C) can be higher than the hot side outlet temperature (60C).
Clarifying your question....are you asking if the cooling medium outlet temp can be higher than the outlet temp of the product being cooled > The answer is No..... if you were to stop the flow and allow the cooling medium to reach equilibrium, then its temp. will be equal to the product temp....under any flowing condition the cooling medium will exit , somewhat lower than the product's temp.
