In view of the Three North areas existing wind power absorption and environment pollution problems,the previous scholars have improved the wind abandon problem by adding electrothermal coupling equipment or optimizing...In view of the Three North areas existing wind power absorption and environment pollution problems,the previous scholars have improved the wind abandon problem by adding electrothermal coupling equipment or optimizing power grid operation.In this paper,an electrothermal integrated energy system including heat pump and thermal storage units was proposed.The scheduling model was based on the load data and the output characteristics of power units,each power unit capacity was programmed without constraints,and the proposed scheduling model was compared with the traditional combined heat and power scheduling model.Results showed that the investment and pollutant discharge of the system was reduced respectively.Wind power was fully absorbed.Compared with the traditional thermal power unit,the proportion of the output was significantly decreased by the proposed model.The proposed system could provide a new prospect for wind power absorption and environment protection.展开更多
Metal foam and fins are two popular structures that are employed to enhance the heat transfer of phase change materials in shell-and-tube heat storage units.However,it remains unclear which structure is better in term...Metal foam and fins are two popular structures that are employed to enhance the heat transfer of phase change materials in shell-and-tube heat storage units.However,it remains unclear which structure is better in terms of energy storage performance.In this study,the heat transfer enhancement performances of metal foam and fins are compared to provide guidance on the optimal structure to be chosen for practical applications.Three fin structures(four fins,two vertical fins,and two horizontal fins)are considered.Under the full configuration(volume fraction of metal=3%),the unit with four fins was found to have a faster melting rate than those with vertical or horizontal fins.In other words,increasing the number of fins helps to accelerate the melting process.Nevertheless,the unit with metal foam enhancement has the highest melting rate.Under the half configuration(volume fraction of metal=1.5%),the melting rate of the unit enhanced by metal foam is significantly decreased,whereas there is no remarkable changes in the units enhanced by fins.However,metal foam is still shown to be the best thermal enhancer.The energy storage rate of the unit enhanced by metal foam can be up to 10 times higher than that of the unit enhanced by fins.展开更多
The use of cold thermal storage systems in low-temperature industrial applications is considered one of the most promising ways of improving energy efficiency and reducing the use of power during peak periods.In this ...The use of cold thermal storage systems in low-temperature industrial applications is considered one of the most promising ways of improving energy efficiency and reducing the use of power during peak periods.In this study,the thermal performance of a shell-and-tube cold storage system under realistic operating conditions is investigated numerically.The proposed model is developed based on energy balances and then validated using existing experimental data from the literature.Glycol/water is used as the heat transfer fluid(HTF)and the phase transition phenomena in the phase change material(PCM)is simulated using the enthalpy-porosity approach.The influence of several design and operating parameters,including the HTF mass flow rate,HTF temperature,PCM type,and volume,on the cold storage performance during the crystallization process is presented and analyzed.The numerical results show that increasing the HTF mass flow rate accelerates the PCM crystallization process.However,the delivery periods of constant thermal power and constant HTF outlet temperature are reduced.The HTF inlet temperature has a significant effect on the cold storage performance,and the complete charging period is reduced by approximately 37%when the HTF inlet temperature is reduced from−4°C to−7°C.Increasing the number of tubes in the cold storage unit is concluded to significantly improve the thermal performance of the system,and using water/ice as a cold storage medium is more suitable than using the commercial PCMs RT2-HC and RT4-HC.Finally,the proposed numerical model for cold storage systems can be successfully used to design and simulate their realistic operation under different conditions.展开更多
基金the fund program of research on re-electrification(heat pump clean heating)to promote the new energy consumption in Shaanxi power grid(5226KY18002P).
文摘In view of the Three North areas existing wind power absorption and environment pollution problems,the previous scholars have improved the wind abandon problem by adding electrothermal coupling equipment or optimizing power grid operation.In this paper,an electrothermal integrated energy system including heat pump and thermal storage units was proposed.The scheduling model was based on the load data and the output characteristics of power units,each power unit capacity was programmed without constraints,and the proposed scheduling model was compared with the traditional combined heat and power scheduling model.Results showed that the investment and pollutant discharge of the system was reduced respectively.Wind power was fully absorbed.Compared with the traditional thermal power unit,the proportion of the output was significantly decreased by the proposed model.The proposed system could provide a new prospect for wind power absorption and environment protection.
基金supported by the National Key R&D Program of China(Grant No.:2018YFA0702300)H2020-MSCA-RISE-778104-ThermaSMARTthe Doctoral Degree Scholarship offered by the China Scholarship Council(CSC).
文摘Metal foam and fins are two popular structures that are employed to enhance the heat transfer of phase change materials in shell-and-tube heat storage units.However,it remains unclear which structure is better in terms of energy storage performance.In this study,the heat transfer enhancement performances of metal foam and fins are compared to provide guidance on the optimal structure to be chosen for practical applications.Three fin structures(four fins,two vertical fins,and two horizontal fins)are considered.Under the full configuration(volume fraction of metal=3%),the unit with four fins was found to have a faster melting rate than those with vertical or horizontal fins.In other words,increasing the number of fins helps to accelerate the melting process.Nevertheless,the unit with metal foam enhancement has the highest melting rate.Under the half configuration(volume fraction of metal=1.5%),the melting rate of the unit enhanced by metal foam is significantly decreased,whereas there is no remarkable changes in the units enhanced by fins.However,metal foam is still shown to be the best thermal enhancer.The energy storage rate of the unit enhanced by metal foam can be up to 10 times higher than that of the unit enhanced by fins.
文摘The use of cold thermal storage systems in low-temperature industrial applications is considered one of the most promising ways of improving energy efficiency and reducing the use of power during peak periods.In this study,the thermal performance of a shell-and-tube cold storage system under realistic operating conditions is investigated numerically.The proposed model is developed based on energy balances and then validated using existing experimental data from the literature.Glycol/water is used as the heat transfer fluid(HTF)and the phase transition phenomena in the phase change material(PCM)is simulated using the enthalpy-porosity approach.The influence of several design and operating parameters,including the HTF mass flow rate,HTF temperature,PCM type,and volume,on the cold storage performance during the crystallization process is presented and analyzed.The numerical results show that increasing the HTF mass flow rate accelerates the PCM crystallization process.However,the delivery periods of constant thermal power and constant HTF outlet temperature are reduced.The HTF inlet temperature has a significant effect on the cold storage performance,and the complete charging period is reduced by approximately 37%when the HTF inlet temperature is reduced from−4°C to−7°C.Increasing the number of tubes in the cold storage unit is concluded to significantly improve the thermal performance of the system,and using water/ice as a cold storage medium is more suitable than using the commercial PCMs RT2-HC and RT4-HC.Finally,the proposed numerical model for cold storage systems can be successfully used to design and simulate their realistic operation under different conditions.
