The series of heat exchangers shown in Figure P5.33 is designed to raise a liquid’s temperature so a desired chemical reaction can take place in the reactor. The specific heat of the liquid can be assumed constant at an average value of 3.2 kJ/kg-K.
The liquid flow rate is 1.4 kg/s. The temperature of the liquid entering HX 1 is 300 K and the temperature leaving the reactor is 390 K. The UA value of HX 1 is 2.88 kW/K. Saturated vapor steam is supplied to HX 2 at 375 K and saturated liquid condensate leaves at 375 K. The UA values of HX 2 and HX 3 are 4.7 kW/K and 9.6 kW/K, respectively. Determine the values of the unknown temperatures (K) in the system and the heat transfer rates in each of the three heat exchangers.

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T = 300 K 7 HX 1 UA = 2.88 kW/K Saturated vapor steam T, = 375 K 2 HX 2 UA = 4.7 KW/K T, = 375 K Saturated liquid steam 6 FIGURE P5.33 Heat exchangers used to control a chemical reaction. 3 HX 3 wwwww UA, = 9.6 kW/K 5 Ts = 390 K Reactor