A shell-and-tube heat exchanger with one shell pass and two tube passes is used as a regenerator, to pre- heat milk before it is pasteurized. Cold milk enters the regenerator at Tc,i 5°C, while hot milk, which has completed the pasteurization process, enters at Th,i 70°C. After leaving the regenerator, the heated milk enters a second heat exchanger, which raises its temperature from Tc,o to 70°C.
Gas and the burner has an efficiency of 90%, what would be the annual savings in energy and fuel costs associated with installation of the regenerator? The facility operates continuously throughout the year, and the cost of natural gas is Cng $0.02/MJ.