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[en] Highlights: • A grid-connected CCHP system with CAES and hybrid refrigeration is proposed. • A multi-objective assessment and optimization is presented. • Each component capacity of the CCHP system is determined by optimization. • A sensitivity analysis is conducted by the key parameters of the system. • Performance comparison with conventional CCHP system has been done. - Abstract: As one of attractive technology of energy conservation, combined cooling, heating and power (CCHP) system has brought about widespread attention. However, the variability of users demand has limited the application of CCHP system. To ensure stable and efficient operation, the compressed air energy storage is considered to be integrated with CCHP system. A grid-connected CCHP system with compressed air energy storage (CAES) and hybrid refrigeration is proposed in this paper. The power from grid is stored in CAES at off-peak time and released at on-peak time. The hybrid refrigeration system including LiBr absorption chiller and electric compression refrigerator provides cooling load to users. A multi-objective assessment and optimization synthetically considering energy, economy and environment are presented. The multi-objective indicator used as objective function to optimize each component capacity of the proposed CCHP system. A sensitive analysis of key parameters and performance comparison with conventional CCHP system have been carried out. The results shows that when the capacity of gas turbine is 691 kW, the comprehensive performance of the proposed CCHP system is the optimal performance. The power price, natural gas price, compression ratio and turbine inlet temperature of CAES have great influence on the performance of the proposed CCHP system. Meanwhile, the multi-objective indicator’s value of the proposed CCHP system is more than conventional CCHP system 4.85%.
[en] Highlights: • An adjacently internally-cooled plate membrane liquid desiccant dehumidifier (AIMLDD) is applied. • The AIMLDD is used for liquid desiccant air dehumidification. • A lumped parameter model is established to study the heat and mass transports in the AIMLDD. • An analytical solution of the performances are obtained and experimentally validated. • The performances of the AIMLDD are about 3.3–9.1% larger than those of the cooling tube type. - Abstract: An adjacently internally-cooled plate membrane liquid desiccant dehumidifier (AIMLDD) is like a four-fluid heat and mass exchanger. The feed air and the solution streams flow in the neighboring channels formed by plate membranes. The water falling film and the sweeping air stream flow in the cooling channel formed by two plastic plates. Absorption heat generated in the solution by absorbing the water vapor transferred from the feed air across the membranes can be taken away by the water. A lumped parameter model is established in a unit cell containing half of a feed air channel, a membrane, a solution channel, and half of a cooling channel, to study the heat and mass transports in the AIMLDD. An analytical solution of the normalized governing equations is obtained. Cooling effectiveness, dehumidification effectiveness, dehumidification rate, energy transfer rate of the feed air, and the ratio of the sensible heat transfer rate of the water to the energy transfer rate are calculated and experimentally validated. The performances of the AIMLDD are compared with those of an internally-cooled plate membrane liquid desiccant dehumidifier with cooling tubes inside the solution channels (IMLDD). The performances of the AIMLDD are about 3.3–9.1% larger than those of the IMLDD.
[en] This paper investigates the interaction between the heat transfer performance and the thermal efficiency of a molten salt receiver used in the solar power tower plant. A test-bed is built, and a series of experiments of heat transfer enhancement for two types of molten salt receiver tubes, including smooth and spiral tubes, have been carried out under the high temperature and the high heat flux conditions. The experimental results show that the Nusselt numbers of spiral tube with heat transfer enhancement are in the range of 400-1200, which is about 3 times than that of the smooth one on average. The wall temperature of the spiral tube is decreased by about 30 oC comparing with that of the smooth tube under the identical heat transfer conditions. The results of the experiment show that, by using the spiral tube as the heat transfer tube, the heat transfer performance of the molten salt receiver is obviously improved, and the radiation and convection losses are significantly reduced. The results will be helpful for the design of the molten salt receiver.