(a) With the aid of a diagram, explain the concept of cogeneration and trigeneration in a power plant.

(b) A trigeneration system can cover cooling and power load that are commonly covered by a centralized power plant and air-conditioner in a conventional energy system. As an engineer, we need to clarify the efficiency and environmental performance of a trigeneration system compared to a conventional energy system as shown in Table 3. The emission of a typical prime mover is shown in Table 4. The fuel input of the trigeneration system is set to be 500 kW. By Assuming the cooling and power output of the conventional system is equal with the output of the trigeneration system;

i) Sketch the energy flow and amount in kW for all stages in a diagram.

ii) Compare the overall efficiency of both systems.

iii) Analyze emissions produced by both systems in 24 hours.

 

Table 3 Conventional Gas Turbine Power Plant with Electric Heater and Air-conditioner Parameter Value 40 2.5 95 8 Power generation efficiency [%] Air-conditioner Coefficient of Performance, COP Electric Heater Efficiency [%] Electricity Transmission & Distribution loss [%] Micro Turbine with Heat Recovery and Absorption Chiller Parameter Power generation efficiency [%] Heat recovery efficiency [%] Percentage of heat used for heating [%] COP of the absorption chiller Micro Turbine Gas Turbine Emissions rate Table 4 CO (g/kWh) 750 655 NOX (g/kWh) 0.22 0.3 Value 40 50 45 0.85 CO (g/kWh) 0.51 0.45