The thermal analysis of an industrial hot water spray washing machine using hot air from the combustion of diesel fuel to heat up water that flows through a spirally coiled steel tube heat exchanger inside a steel shell combustion chamber was analyzed. The working fluids used are water and air. The spirally coiled tube is made by bending a 15mm diameter and 3 mm thick straight pipe into 4 turns and 9 layers respectively. The total length of the tube is approximately 20m. Water at ambient temperature flows into the coil through the outermost turn and flows out through the innermost turn. The adiabatic flame temperature of the fuel was determined. The in-tube and the outside convective heat transfer coefficients were determined using the appropriate correlations available in literature. A mathematical model of the heat transferred to the water was formulated and solved using the Engineering Equation Solver (EES). The results obtained are in reasonable agreement with measured data. Parametric study was done to determine the effects of each parameter on the outlet water temperature.
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