1. Heat Exchanger. I have some hot oil at 250 C I need to cool to 100 Cusing a stream of cold oil at 50 C. Lets say we have 100 kg/min of hot oil.I am going to do this in a heat exchanger which brings the fluids in thermal but not physical contact (ie the fluids are in their own tubes and don't mix, but do exchange heat). The specific heat of both oils is 1.5cal/(g°C). If I don't want the cold oil to get over 80 C, what flowrate of cold oil is required? You may want to start by figuring out how much heat the hot oil must lose and realise that is how much the cold oil must gain.