In this paper, through two case studies, evaporation systems are considered in the context of overall process, and then are optimized to obtain energy-saving effect. The possible evaporation schemes are given when int...In this paper, through two case studies, evaporation systems are considered in the context of overall process, and then are optimized to obtain energy-saving effect. The possible evaporation schemes are given when integrated with the background process and how to optimize the evaporator is shown. From the case studies, it can be seen that sometimes incomplete integration and heat pump evaporation are better than complete integration so should be considered as candidate retrofit schemes.展开更多
Based on the boron-containing thermally activated delayed fuorescence(TADF)compound p-AC(AC:acridine)5,9-dioxa-13 b-boranaphtho[3,2,1-de]anthracene(a),a series of new TADF molecules b1-b4 were designed via adding two ...Based on the boron-containing thermally activated delayed fuorescence(TADF)compound p-AC(AC:acridine)5,9-dioxa-13 b-boranaphtho[3,2,1-de]anthracene(a),a series of new TADF molecules b1-b4 were designed via adding two nitrogen atoms at the AC donor part.Density functional theory and time-dependent density functional theory calculations were performed on the frontier orbital energy levels,emission spectra,singlet-triplet states energy gaps(?EST),reverse intersystem crossing(RISC)rate constant(kRISC)for compounds a and b1-b4.Our calculation results show that the maximum emission wavelengths of b1-b4 are significantly blue-shifted by47-125 nm compared with that of a.Molecules b1 and b3 exhibit dark-blue emission,while molecules b2 and b4 display light-blue emission,indicating that these four derivatives could be potential organic light-emitting diode(OLED)candidates with blue-light emitting.Moreover,we found the RISC processes in a,b2,and b4 can occur not only from T_(1) state to S_(1) state,but also from T_(2) state to S_(1) state significantly,while the RISC processes in b1 and b3 mainly take place via the T_(2)→S_(1) hot exciton way.Importantly,the T_(1)→S_(1) kRISC values of b2 and b4 are predicted to be two to three times of that of a,indicating enhanced TADF property.Our results not only provide two promising boron-based TADF candidates(b2 and b4),but also offer useful theoretical basis for the design of blue OLED materials.展开更多
A numerical study based on direct thermal to electric energy conversion was performed in a reciprocal flow porous media burner embedded with two layers of thermoelements. The burner lean combustibility limit was sough...A numerical study based on direct thermal to electric energy conversion was performed in a reciprocal flow porous media burner embedded with two layers of thermoelements. The burner lean combustibility limit was sought in order to maximize global efficiency of thermal to electrical energy conversion by minimizing fuel consumption. Once the pairs of operational variables, composition and filtrational velocity of gas inlet mixture were found, the optimal length and placement of thermoelectric elements within the reactor high thermal gradients were sought to maximize the electric current, thermoelements and system overall efficiency. A two temperature-resistance model for finite time thermodynamics was developed for the thermoelectric elements energy fluxes. Results indicate a distribution of current and efficiencies that presents a maximum at different themoelements length. Maximum values for current and system efficiency obtained were 44.3 m A and 2.5%, respectively.展开更多
The reasons of introducing cold air into pulverizer are analyzed for boilers with large capacity and high parameters. The temperature rises of the exhaust gas are calculated when varying the amount of the cold air. Th...The reasons of introducing cold air into pulverizer are analyzed for boilers with large capacity and high parameters. The temperature rises of the exhaust gas are calculated when varying the amount of the cold air. The hot primary air heater, a new technology, is developed to eliminate the cold air from the pulverized coal system. The applications, advantages and disadvantages are introduced in detail for the new device and system. It is concluded that introducing cold air into pulverizer is one of the major factors that causes the exhaust gas temperature of boilers with large capacity to be high. The amount of the cold air could be reduced signif icantly, even to zero in some cases by adopting the hot primary air heater, which drops the exhaust gas temperature of the boiler effectively. The hot primary air heater, which could play part roles of the steam-air heater or the hot air recirculation system, could also be used to adjust the exhaust gas temperature within the range of 20 ℃ by controlling the flow rate of the cooling medium. Moreover, the startup period of the steam-air heater or the hot air recirculation system will be shortened, which is a unique advantage of the hot primary air heater among the measures to drop the exhaust gas temperature.展开更多
文摘In this paper, through two case studies, evaporation systems are considered in the context of overall process, and then are optimized to obtain energy-saving effect. The possible evaporation schemes are given when integrated with the background process and how to optimize the evaporator is shown. From the case studies, it can be seen that sometimes incomplete integration and heat pump evaporation are better than complete integration so should be considered as candidate retrofit schemes.
基金supported by the National Natural Science Foundation of China(No.22173008)。
文摘Based on the boron-containing thermally activated delayed fuorescence(TADF)compound p-AC(AC:acridine)5,9-dioxa-13 b-boranaphtho[3,2,1-de]anthracene(a),a series of new TADF molecules b1-b4 were designed via adding two nitrogen atoms at the AC donor part.Density functional theory and time-dependent density functional theory calculations were performed on the frontier orbital energy levels,emission spectra,singlet-triplet states energy gaps(?EST),reverse intersystem crossing(RISC)rate constant(kRISC)for compounds a and b1-b4.Our calculation results show that the maximum emission wavelengths of b1-b4 are significantly blue-shifted by47-125 nm compared with that of a.Molecules b1 and b3 exhibit dark-blue emission,while molecules b2 and b4 display light-blue emission,indicating that these four derivatives could be potential organic light-emitting diode(OLED)candidates with blue-light emitting.Moreover,we found the RISC processes in a,b2,and b4 can occur not only from T_(1) state to S_(1) state,but also from T_(2) state to S_(1) state significantly,while the RISC processes in b1 and b3 mainly take place via the T_(2)→S_(1) hot exciton way.Importantly,the T_(1)→S_(1) kRISC values of b2 and b4 are predicted to be two to three times of that of a,indicating enhanced TADF property.Our results not only provide two promising boron-based TADF candidates(b2 and b4),but also offer useful theoretical basis for the design of blue OLED materials.
文摘A numerical study based on direct thermal to electric energy conversion was performed in a reciprocal flow porous media burner embedded with two layers of thermoelements. The burner lean combustibility limit was sought in order to maximize global efficiency of thermal to electrical energy conversion by minimizing fuel consumption. Once the pairs of operational variables, composition and filtrational velocity of gas inlet mixture were found, the optimal length and placement of thermoelectric elements within the reactor high thermal gradients were sought to maximize the electric current, thermoelements and system overall efficiency. A two temperature-resistance model for finite time thermodynamics was developed for the thermoelectric elements energy fluxes. Results indicate a distribution of current and efficiencies that presents a maximum at different themoelements length. Maximum values for current and system efficiency obtained were 44.3 m A and 2.5%, respectively.
文摘The reasons of introducing cold air into pulverizer are analyzed for boilers with large capacity and high parameters. The temperature rises of the exhaust gas are calculated when varying the amount of the cold air. The hot primary air heater, a new technology, is developed to eliminate the cold air from the pulverized coal system. The applications, advantages and disadvantages are introduced in detail for the new device and system. It is concluded that introducing cold air into pulverizer is one of the major factors that causes the exhaust gas temperature of boilers with large capacity to be high. The amount of the cold air could be reduced signif icantly, even to zero in some cases by adopting the hot primary air heater, which drops the exhaust gas temperature of the boiler effectively. The hot primary air heater, which could play part roles of the steam-air heater or the hot air recirculation system, could also be used to adjust the exhaust gas temperature within the range of 20 ℃ by controlling the flow rate of the cooling medium. Moreover, the startup period of the steam-air heater or the hot air recirculation system will be shortened, which is a unique advantage of the hot primary air heater among the measures to drop the exhaust gas temperature.
