---

In this article, after the design of a CCHP system for office buildings in Tehran, a mathematical analysis of the CCHP system following thermal demand management in comparison to separate system is presented. In order to have a comprehensive evaluation of the performance of the CCHP system, four criteria including primary energy saving, CO2 emission reduction, operational cost reduction and rate of return are employed for a typical office building in Iran. Also a sensitivity analysis of rate of return based on increasing natural gas and electric price is performed. Results show that the CCHP system with selling electricity to grid has much better performance than separate system when all of the criteria are involved. Also without selling electricity to grid the CCHP system achieves more benefits than separate system but these benefits are less than the benefits of the situation with selling electricity to grid. The sensitivity analysis shows that in the situation with selling electricity to grid, with increasing natural gas and electric price the ROR will be increased but in the situation without selling electricity to gird, with 40% increase in natural gas price the ROR will become less than Interest Rate.

---

In this article, a mathematical analysis of a CCHP system following electrical demand management and thermal demand management in comparison to separate heat and power system for an office building in Tehran is presented. In the thermal demand management, two modes including with selling electricity to grid and without selling electricity to grid are investigated. In order to have a comprehensive evaluation of the performance of the CCHP system, four criteria including primary energy saving, CO2 emission reduction, operational cost reduction and rate of return are employed for a typical office building in Iran. Also the AHP method is used to specify the best operation mode of the CCHP system when all of the criteria are involved. Results show that from the energy and environmental viewpoints, the CCHP system following thermal demand management with selling electricity to the grid is the best operation mode. But the CCHP system following electrical demand management has the maximum rate of return. For the all of the operation modes, the CCHP system has lower operational cost than SHP system throughout the year. From an integrated view point, the CCHP system following thermal demand management with selling electricity to the grid is the most attractive option.

---

In this paper, optimization and techno-economic evaluation of a Combined Cooling, Heating and Power ( CCHP ) system for a hotel in Kerman has been investigated. The design parameters of system includes capacity of gas engine (as prime mover), partial load (PL), thermal capacity of boiler, the cooling capacities of electric and absorption chillers that by using energy, economic, and environment analysis and relative annual benefit (AP), as objective function, have been optimized. Then for optimum results the payback period (PB) has been investigated, by considering the time value of money and without it. Results show increase of number prime mover, reduce the annual benefit and this process has reverse relation with classic payback period since choosing a 2550 kW gas engine, maximum relative annual benefit (AP) with value of 45.5×105 ($/year) and minimum payback period (PB) of 6 years obtains. Also when the costs of energy increases and one prime mover (PM) is selected, the results of traditional and classical payback method are different as the time of payback period increase in classic method and decrease for traditional method.

---

In present paper, the effect of combined cooling, heating and power generation systems(CCHP) in the reduction of pollutants emission have been investigated and a hotel with 80 rooms in Zahedan have been selected as case study , also gas engine (With part-load operation) as prime mover for design CCHP system. In this work is assumed that sell electricity to grid is possible. At the first phase, optimization for access to maximum reduce Pollutants emission have been done, at the other phase, a multi-criteria function has been introduced and the optimization process, with Percentage of Relative Annual Benefit (PRAB) has been investigated and the results of these two phases, have been compared together. Results show, CCHP systems have a high effect in reduce environmental pollutants emission CO, CO2 and NOx, as the percent reduce pollutants emission is positive in an extensive range of nominal power of gas engine. Also results show for access to maximum reduce pollutants emissions , CO2, CO and NOx, annual benefit as multi-ceritria objective function a gas engine with nominal power 2050kW is needed; in this case in addition to the most annual benefit also have a good effect for reducing Pollutants emission. In the end, the effect of the number of prime mover as designing parameter assessed with increase from one into two and three numbers. Results show increasing prime mover, cause decrease Relative Annual Benefit and pollutants emission.

---

In this paper a combined cooling heating and power system for using heat losses in PEM fuel cell has been proposed, present system can use for residential application. This system consists of PEM fuel cell, Heat storage tank, absorption chiller, hydrogen tank, air compressor and pump. Heat generated in fuel cell has been absorbed by a working fluid and a part of heat has been given to absorption chiller and another part has been given to heat storage tank. Modeling of this system has been done from four energy, exergy, FESR and CDER perspective. Fuel cell of this CCHP system generates 38.63 kW electrical power and 39.17 kW heat power. Energy efficiency of fuel cell singly is 37.21% but when heat storage tank and absorption chiller has been used for recovering waste heat, energy efficiency reaches to 68%. Maximum irreversibility loss occurs in fuel cell which is calculated 47.21 kW and absorption chiller irreversibility has been calculated 5.94 kW. From viewpoint of FESR and CDER in comparison with conventional systems, FESR and CDER are 34% and 25% respectively. Also analyzes had been showed that with increasing fuel cell operating pressure energy and exergy efficiency increased and by increasing high pressure of chiller COP decreased

---

In the present paper, a gas turbine (GT) unit with nominal capacity of 26.8 MWe, which is used for continuous production of electricity in Ilam Gas Refinery Company, has been investigated for combined production of cooling, heating, power and process (CCHPP). Critical parameters are measured and the potentials of transforming the GT unit to CCHPP are investigated from technical, economic, and environmental point of views. A heat recovery steam generator (HRSG) converts the exhaust energy to steam that can be used for three purposes of cooling, heating and process. The cycle is first evaluated thermodynamically, and to be certain about the HRSG, its operation is studied by using the pinch technology. Economical evaluation is carried out by calculating initial investment, payback period, net present value (NPV) and internal rate of return. In addition the impact of using CCHPP on reduction of environment pollutant gases such as CO, CO2, and NOx is studied. The results reveal that, the fuel energy saving ratio of 36% is achieved for the minimum pinch point temperature of 19 ̊ C in the HRSG unit. The payback period is only 5.2 year, and the NPV during the project lifetime is 1.87 M$. In addition the CO2, CO, and NOx reduction is about 32000, 22 and 27 tons/year respectively.