Conventional Combined Cooling, Heating And Power System Research Articles

Investigation of the Cofiring of Methane and Biosyngas for Combined Cooling, Heating, and Power Generation with Zero Carbon Dioxide Emissions

AbstractA new chemical looping combustion (CLC) of biosyngas and methane in a system with combined cooling, heating, and power (CCHP) is presented. The aim of the integration of CLC into the CCHP system is to obtain zero CO2 emissions and to reduce exergy destruction within the combustion process. With the increase in the biomass‐to‐methane mass ratio from 0 to 1 (referred to as 100 %), the total energy output increases from 637.17 to 746.62 kW, and there is a simultaneous reduction of both the energy and exergy efficiencies from 91.70 to 82.10 % and from 43.32 to 37.84 %, respectively. However, the primary energy savings ratio benefits from an increase of the biomass mass ratio (from 0 to 1) and increases from 42.80 to 46.36 %. Furthermore, a conventional CCHP system is developed and simulated for comparison. To discuss the feasibility of this process, the effect of the gas conversion ratio in the CLC system on the overall efficiency was analyzed and the autothermal operation strategy of CLC was considered.

Thermodynamic boundaries of energy saving in conventional CCHP (Combined Cooling, Heating and Power) systems

In this research, an improved calculational method of ESR (energy saving rate) considering energy adjustments caused by climate effects is presented based on international standards or regulations regarding energy management. The indicator of “general heat-to-electricity ratio” (R) is proposed to illustrate the energy configurations of CCHP (Combined Cooling, Heating and Power) systems and their potential users. Theoretical calculations of “thermodynamic boundaries” incorporating the general heat-to-electricity ratio as well as the maximum of ESR have been discussed in the mode of “priority of providing cooling” to find the most suitable users for CCHP systems and to envision the energy saving potentials of CCHP systems. Moreover, investigation of CCHP systems in China in terms of ESR distribution has been undertaken to corroborate the theoretical calculations. Theoretical results show that the most suitable CCHP users should have their general heat-to-electricity ratios valued in the range of 0.9–2.8 (without heating demand) or 0.65–1.3 (with heating demand). Furthermore, particularly in Beijing, the maximums of ESR of CCHP systems without and with heating demand cases are 32.5% and 38%, respectively. Deviations between the investigation and theoretical calculations can be partially attributed to the assumptions, which have also been discussed.

Hybrid CCHP system combined with compressed air energy storage

This study proposes a novel combined cooling, heating and power (CCHP) system with compressed air energy storage (CAES). By storing or releasing the electricity using CAES, the performance of this proposed system is improved, solving the low efficiency problem of gas turbine due to the off-design working condition. Meanwhile, with the energy storage of heat and cold, the proposed system can work with high efficiency under the condition of meeting the users' energy demand. The system is optimized to minimize the fuel consumption and maximize the exergy efficiency subject to the energy demand. Its thermodynamic performance and the effects of its key parameters are evaluated. As a result, the gas turbine (GT) power of the new system is 30.4% smaller than that of the conventional CCHP, with the fuel energy saving ratio (FESR) as high as 29.4%. This study provides a significantly alternative option for the cogeneration system by combining the CAES into conventional CCHP system. Copyright (c) 2015 John Wiley & Sons, Ltd.

Complementary configuration and operation of a CCHP-ORC system

The electricity to thermal energy output ratio is an important impact factor for the operating modes and performances of combined cooling, heating and power (CCHP) systems. If the energy requirements of users are managed to just match this ration, the system efficiency would reach the maximum. However, due to the randomness of load demands, this situation is rare to be achieved in practice. To solve this problem, a complementary CCHP-ORC system is configured in this paper. The salient feature of this system is that its electricity to thermal energy output ratio can be adjusted by changing the loads of electric chiller and organic Rankine cycle (ORC) dynamically. For this system, an optimal operation strategy and a corresponding implemented decision making process are presented within a wide load range. Case studies based on a hypothetical CCHP-ORC system for a hotel in Beijing are implemented. The results show that the primary energy consumption, the carbon dioxide emissions and the operation cost of the proposed CCHP-ORC system are all better than those of the conventional CCHP system.

Performance study of an innovative natural gas CHP system

In the last decade, technological innovation and changes in the economic and regulatory environment have resulted in increased attention to distributed energy systems (DES). Combined cooling heating and power (CHP) systems based on the gas-powered internal combustion engine (ICE) are increasingly used as small-scale distribution co-generators. This paper describes an innovative ICE–CHP system with an exhaust-gas-driven absorption heat pump (AHP) that has been set up at the energy-saving building in Beijing, China. The system is composed of an ICE, an exhaust-gas-driven AHP, and a flue gas condensation heat exchanger (CHE), which could recover both the sensible and latent heat of the flue gas. The steady performance and dynamic response of the innovative CHP system with different operation modes were tested. The results show that the system’s energy utilization efficiency could reach above 90% based on lower heating value (LHV) of natural gas; that is, the innovative CHP system could increase the heat utilization efficiency 10% compared to conventional CHP systems, and the thermally activated components of the system have much more thermal inertia than the electricity generation component. The detailed test results provide important insight into CHP performance characteristics and could be valuable references for the control of CHP systems. The novel CHP system could take on a very important role in the CHP market.