5. Consider that the flow rates of hot and cold-water streams running through a parallel-flow heat exchanger are 0.3 kg/s and 0.55 kg/s respectively, shown in Fig. 2. The inlet temperatures on the hot and cold sides are 85°C and 20°C respectively. The exit temperature of hot water is 48°C. 4-20°C -75°C 4₁ = 20°C Cold water Hot water Cold water (a) Flow arrangement. 45°C (ing) = 75°C Hot water Temperature 45°C Cold water -20°C Fig. 2 Parallel-flow heat exchanger Area/Length- (b) Temperature distribution. a. If the individual heat transfer coefficients on both sides are 640 W/m2 °C, apply the heat transfer formulae to calculate the area of the heat exchanger. (4 marks) b. Recalculate the area if the flow was a counter-flow (2 marks)

Fig: 1