A seasonal food processing industry currently meets its demand for heat and electrical power by purchasing electricity from the local utility and generating heat from a natural gas fired boiler. The Energy manager is considering an alternative supply using a stirling engine based CHP $($combined heat and power$)$ unit also using natural gas, whcih will be sized according to the electrical and thermal loads of the summer months, $3$ kW and $118\mathrm{.}8$ MJ$/$hr$,$ respectively. In winter the extra heating requirements will be met by the exisiting boiler and extra electricity purchased from the local utility. It is intended that the CHP unit will run at full load for $16$ hours per day, everyday of the year. The overall efficiency of the CHP unit is $85\%.$ The capital cost of the CHP unit is $6000$ euro, while annual maintanance cost of unit is $500$ euro. The natural gas adn electricity tariff are $3\mathrm{.}6$ euro$/$GJ and $42$ euro$/$Mwh$,$ respectively. The existiing natural gas fired boiler has an efficiency of $80\%.$ The heating value of natrual gas is $38$ MJ$/$Sm$^3.$

 

 

a$)$ Outline the design and operation of the proposed CHP system using appropriate schematics $($including a 'heat balance' diagram for the CHP unit$)$ to illustrate your answer.

b$)$ Draw an annual 'balance of energy demand' diagram comparing the existing and propsed energy supply systems and hence determine the capacifty factor fo the CHP unit, the change in natural gas hourly columetric flow rate between the CHP uinit and the exisiting boiler, the net annual savings in energy costs and the resultant simple payback time for the capital investment required.

Answer rating: 100% (QA)

a Outline the design and operation of the proposed CHP system using appropriate schematics A Combined Heat and Power CHP system also known as cogeneration can simultaneously produce electricity and us... View the full answer