The cogeneration gas-turbine cycle can be augmented with a heat pump to extract more energy from the turbine exhaust gas, as shown in Fig. P11.194. The heat pump upgrades the energy to be delivered at the 70◦Cline for district heating. In the modified application, the first heat exchanger has exit temperature T₆a = T₇a = 45◦C, and the second one has T₆b = T₇b = 36◦C. Assume the district heating line has the same exit temperature as before, so this arrangement allows for a higher flowrate. Estimate the increase in the district heating load that can be obtained and the necessary work input to the heat pump.

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70°C Heat W HP pump 40°C 5) 6a 6b Sat. air to chimney 135°C (7a) (7b) FIGURE P11.194