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[en] Highlights: • Study on boundary conditions of five kinds of adsorption heat pumps is presented. • Feasibility and economic studies under various working conditions were made. • Suggested ranges of driving and cooling temperatures are given for economic use. - Abstract: The objectives of this paper are to analyze adsorption heat pump (AHP) systems using different working pairs such as silica gel/water, zeolite/water, SAPO-34/water, FAPO-34/water and activated carbon/ammonia, and to carry out their boundary conditions. According to the Clapeyron diagram, adsorption equilibrium equations and energy balance equations, feasibility and economic studies under various working conditions are made. Silica gel/water, SAPO-34/water and FAPO-34/water AHPs can feasibly operate for space heating and domestic hot water. Beyond that, zeolite/water and activated carbon/ammonia AHPs can even feasibly operate for heating network or industrial heating/preheating. However, ranges of economic operation are much stricter than that of feasible operation. Silica gel/water, SAPO-34/water and FAPO-34/water AHPs are not convenient for cold winter except zeolite/water and activated carbon/ammonia AHPs. Activated carbon/ammonia AHP even can economically operate in the cold winter with −15 °C ambient temperature. Floor heating is the most convenient technique for silica gel/water, SAPO-34/water and FAPO-34/water AHPs. Zeolite/water and activated carbon/ammonia AHPs require more than 130 °C and more than 140 °C driving source for economic use, respectively. The sequence according to the value of COPH is as follows: silica gel/water, FAPO-34/water, SAPO-34/water, zeolite/water and activated carbon/ammonia AHPs.
[en] Highlights: • A CCHP system integrated with biomass gasification was optimized. • The optimization was based on life-cycle assessment. • The optimization involved energetic, economic, and environmental aspects. • The overall-performance criterion was obtained with TOPSIS. - Abstract: A multi-criteria optimization for a biomass gasification-integrated combined cooling, heating, and power (CCHP) system based on life-cycle assessment is carried out. The criteria comprise primary energy saving ratio (PESR), total cost saving ratio (TCSR), and CO2 emission reduction ratio (CERR). The overall-performance criterion, Cl, is obtained with Technique for Order of Preference by Similarity to Ideal Solutions (TOPSIS). Results show that the Cl reaches its maximum when the nominal electric output is 1572.8 kW, the biomass feedstock type is wood pellet, and the operation strategy is following the electric load (FEL). The PESR, TCSR, CERR, and Cl are 0.101, 0.271, 0.498, and 0.867, respectively. By comparing with reference systems, it is found that in FEL mode, the system is improved because of higher energy utilization efficiency and better use of economic and environmental advantages of biomass. In following the thermal load (FTL) mode, economic performance is compromised for optimal overall performance. Sensitivity analysis is carried out to find out the effect of variation of various parameters on optimization results. It is found that the variation of a single-aspect parameter could affect the system performance on all aspects. The variation of primary energy consumption per unit electricity from the grid (pecen,g) has the greatest effect on optimization results. The corresponding variation ranges of PESR, TCSR, and CERR owing to its variation are from −0.063/0.231/0.473 to 0.284/0.295/0.624 and from −0.029/0.101/0.314 to 0.194/0.123/0.379 in FEL and FTL modes.
[en] Highlights: • A sorption thermal energy storage device for domestic heating is presented. • The new design scenario with valve-less adsorber and separate reservoir is adopted. • The newly developed composite sorbent of zeolite 13X/MgSO4/ENG-TSA is used. • The temperature lift is 65–69 °C at 25 °C adsorption and evaporating temperatures. • The impregnated MgSO4 dramatically accelerates the temperature rising rate. - Abstract: A sorption thermal energy storage (TES) device for domestic heating is presented in this article. The TES device adopts the new design scenario with valve-less adsorber and separate reservoir to eliminate the large-diameter vacuum valve for vapor flow, which decreases the cost, reduces the vapor flow resistance, and improves the system reliability. The device is charged by electric heater, which can add much flexibility to the building energy system as well as contribute to the valley filling and peak shaving from the demand side management. The newly developed composite sorbent of zeolite 13X/MgSO4/ENG-TSA (expanded natural graphite treated with sulfuric acid) with the salt mass fraction of 15% in the zeolite 13X/MgSO4 mixture is tested and used in the TES device (denoted as XM15/ENG-TSA). Experimental results show that the TES device with XM15/ENG-TSA has the energy storage density of 120.3 kWh m−3 at 250 °C charging temperature and 25–90 °C discharging temperature. The temperature lift is as high as 65–69 °C under the adsorption and evaporating temperatures of 25 °C. The impregnated MgSO4 dramatically improves the temperature rising rate during the adsorption heat recovery process, but the specific energy storage capacity of XM15/ENG-TSA is similar to that of zeolite 13X/ENG-TSA. The effect of the impregnated MgSO4 suggests that MgSO4 can be used for low-temperature TES to relieve the self-hindrance of the hydration reaction.