Intermittent heating is an energy-saving heating mode,which can save energy in terms of time,and thus is worth promoting,particularly in residential heating scenarios.Conventional radiant heating terminals,that is flo...Intermittent heating is an energy-saving heating mode,which can save energy in terms of time,and thus is worth promoting,particularly in residential heating scenarios.Conventional radiant heating terminals,that is floor heating,and convective heating terminals,that is fan coils,cannot achieve both intermittent and thermal comfort during intermittent heating.Therefore,this study proposes a switchable convective-radiant heating regulation method for floor heating and fan coils to achieve a comfortable indoor environment with high thermal response speed.Furthermore,a novel combined radiant-convective heating terminal was proposed for a reliable and effective solution.Results showed that the proposed switchable method could increase both intermittence and thermal comfort.In addition,the heating terminal showed better heating performance than the combination of two conventional terminals at the key points of heating capacity,flexibility,and thermal response.It could initially heat up a typical residential space within 20-40 min and then stabilize the room temperature in a comfortable range of 18-22℃,showing great potential for intermittent heating in room-scale heating conditions.This study provides a reference technique for intermittent heating with reduced system complexity and precise environmental control.展开更多
Intermittent heating for drying of small diameter Larch lumbers is investigated experimentally. The lumbers were dried using an experimental drying schedule. Moisture content (MC) of the lumber was continuously record...Intermittent heating for drying of small diameter Larch lumbers is investigated experimentally. The lumbers were dried using an experimental drying schedule. Moisture content (MC) of the lumber was continuously recorded and final drying defects were examined. The drying curves showed that the drying rate was a constant in the early stage of intermittent heating drying and decreased evidently when the MC was about 18% (intermittent 2h) and 20% (intermittent 6h). The drying quality reached the second (intermittent 2h) and first grade (intermittent 6h) of the Chinese National Standard. The visual drying defects, especially the check extent along grains were reduced with intermittent heating. When the intermittent time increased, the effect was more obvious.展开更多
In the hot summer&cold winter zone in China,intermittent heating space for rooms is widely used.However,in comparison with continuous space heating,the energy-saving performance of intermittent space heating has n...In the hot summer&cold winter zone in China,intermittent heating space for rooms is widely used.However,in comparison with continuous space heating,the energy-saving performance of intermittent space heating has not been sufficiently investigated.This paper studied the factors influencing the energy performance of intermittent heating for the representativeoffice inhot summer&coldwinter zone.Basedon theheatbalancemethod,adynamic thermalmodel of the intermittent heating roomwas built and tested by experiments.And then,it analyzed the total space heating load,the amount of energy saving and energy saving ratio of the intermittent heating under different preheating hours,occupation hours,required roomtemperatures,air change rates,overall heat transfer coefficients(U-value)of windows and wall materials.If the adjacent rooms were not heated,for a typical room occupied about 10 h a day,the energy-saving ratio of intermittent heating was about 30%compared with continuous heating.But the preheating power was higher than two times of continuous heating.The results also indicated that the occupation hours had a significant effect on energy saving amount and ratio,it should be noted that the energy saving ratio by intermittent heating was much lower than the unoccupied period ratio.Relative to other factors,the heating temperatures,room air change rates and U-value of windows,and room envelope materials had little effect on energy efficiency.If the adjacent rooms were heated in the same manner as the roomin question,the energy-saving ratio of the total load of intermittent heating was heavily reduced to 8.46%.展开更多
Building energy consumption is mainly influenced by thermal load,equipment efficiency,service space,and operating time.While extensive research has focused on reducing load and improving efficiency,significant energy-...Building energy consumption is mainly influenced by thermal load,equipment efficiency,service space,and operating time.While extensive research has focused on reducing load and improving efficiency,significant energy-saving potential remains in optimizing time and space of usage.This study proposes a novel convective-radiant desktop-based terminal that integrates personalized environmental control system with convective-radiant terminals,enabling“part-time,localized-space”operations to enhance energy savings.It includes a discussion on the structural design of the device and experimental analysis of its local environmental control and intermittent operation.The design incorporates a convective heat exchanger and radiant panel embedded in a height-adjustable desktop.Experimental results showed that the combination of the radiant panel and air outlet beneath the desktop accumulates heat in this area during heating,creating a“cool head,warm feet”thermal comfort effect.The maximum vertical temperature difference was 0.7℃ in radiation mode.For intermittent operation,the temperature response matching coefficient(TRMC)of the proposed terminal was 3.4 times that of floor heating and 2.1 times that of fan coil units,indicating superior performance.Besides,this novel terminal provides effective thermal comfort in both sitting and standing positions,offering potential energy savings in open-plan offices.By extending the room temperature setpoint to 16–18℃ in winter,the terminal can reduce energy consumption by 3.64%–12.52%.These findings provide a reference for personalized environmental control systems and intermittent heating strategies.展开更多
To improve heating uniformity and anthocyanin content of the blueberry pulp under microwave heating,the intermittent variable power microwave heating technology was introduced in the study.The effects of technology pa...To improve heating uniformity and anthocyanin content of the blueberry pulp under microwave heating,the intermittent variable power microwave heating technology was introduced in the study.The effects of technology parameters in terms of high microwave intensity heating time,intermittent time,low microwave intensity and low microwave intensity heating time on the blueberry pulp quality parameters(heating uniformity,average moisture content,the highest temperature and anthocyanin content)were investigated by using the response surface method.The results showed that the longer heating time under different microwave intensities resulted in the poorer heating uniformity.The intermittent stage promoted heat and mass transfer within the pulp and reduced the temperature difference and moisture gradient within the pulp,which enhanced desired uniformity of temperature and moisture distribution before entering the low microwave intensity heating stage.Therefore,the longer the intermittent time,the greater the heating uniformity.The optimal parameters were developed as high microwave intensity of 4 W·g^(-1),high microwave intensity heating time of 9.86 min,intermittent time of 10 min,low microwave intensity of 2.2 W·g^(-1)and low microwave intensity heating time of 6 min.This research might provide guidance for microwave heating berry fruits.展开更多
基金supported by the China National Key Research and Development Program"Integrated convection/radiation coupling terminals for local environment"(2022YFC3801502)the National Natural Science Foundation of China(52108082,52130803,and 52394223)+2 种基金the China Postdoctoral Science Foundation(2023M732479)the Natural Science Foundation of Sichuan Province of China(2024NSFSC0916)the New Cornerstone Science Foundation through the XPLORER PRIZE。
文摘Intermittent heating is an energy-saving heating mode,which can save energy in terms of time,and thus is worth promoting,particularly in residential heating scenarios.Conventional radiant heating terminals,that is floor heating,and convective heating terminals,that is fan coils,cannot achieve both intermittent and thermal comfort during intermittent heating.Therefore,this study proposes a switchable convective-radiant heating regulation method for floor heating and fan coils to achieve a comfortable indoor environment with high thermal response speed.Furthermore,a novel combined radiant-convective heating terminal was proposed for a reliable and effective solution.Results showed that the proposed switchable method could increase both intermittence and thermal comfort.In addition,the heating terminal showed better heating performance than the combination of two conventional terminals at the key points of heating capacity,flexibility,and thermal response.It could initially heat up a typical residential space within 20-40 min and then stabilize the room temperature in a comfortable range of 18-22℃,showing great potential for intermittent heating in room-scale heating conditions.This study provides a reference technique for intermittent heating with reduced system complexity and precise environmental control.
基金Sponsored by Huo Yingdong Fund(Grant No.81022) Sponsored by the Science and Technology Project Foundation of Harbin City( Grant No.2004AFX XJ021).
文摘Intermittent heating for drying of small diameter Larch lumbers is investigated experimentally. The lumbers were dried using an experimental drying schedule. Moisture content (MC) of the lumber was continuously recorded and final drying defects were examined. The drying curves showed that the drying rate was a constant in the early stage of intermittent heating drying and decreased evidently when the MC was about 18% (intermittent 2h) and 20% (intermittent 6h). The drying quality reached the second (intermittent 2h) and first grade (intermittent 6h) of the Chinese National Standard. The visual drying defects, especially the check extent along grains were reduced with intermittent heating. When the intermittent time increased, the effect was more obvious.
基金supported by the National Natural Science Foundation of China(No.71974129).
文摘In the hot summer&cold winter zone in China,intermittent heating space for rooms is widely used.However,in comparison with continuous space heating,the energy-saving performance of intermittent space heating has not been sufficiently investigated.This paper studied the factors influencing the energy performance of intermittent heating for the representativeoffice inhot summer&coldwinter zone.Basedon theheatbalancemethod,adynamic thermalmodel of the intermittent heating roomwas built and tested by experiments.And then,it analyzed the total space heating load,the amount of energy saving and energy saving ratio of the intermittent heating under different preheating hours,occupation hours,required roomtemperatures,air change rates,overall heat transfer coefficients(U-value)of windows and wall materials.If the adjacent rooms were not heated,for a typical room occupied about 10 h a day,the energy-saving ratio of intermittent heating was about 30%compared with continuous heating.But the preheating power was higher than two times of continuous heating.The results also indicated that the occupation hours had a significant effect on energy saving amount and ratio,it should be noted that the energy saving ratio by intermittent heating was much lower than the unoccupied period ratio.Relative to other factors,the heating temperatures,room air change rates and U-value of windows,and room envelope materials had little effect on energy efficiency.If the adjacent rooms were heated in the same manner as the roomin question,the energy-saving ratio of the total load of intermittent heating was heavily reduced to 8.46%.
基金supported by the Postdoctoral Fellowship Program of CPSF under Grant Number GZB20240379the National Natural Science Foundation of China(Grant No.52394223,52425801,52130803,and 52408102)the Natural Science Foundation of Jiangsu Province(Grants No.BK20241348).
文摘Building energy consumption is mainly influenced by thermal load,equipment efficiency,service space,and operating time.While extensive research has focused on reducing load and improving efficiency,significant energy-saving potential remains in optimizing time and space of usage.This study proposes a novel convective-radiant desktop-based terminal that integrates personalized environmental control system with convective-radiant terminals,enabling“part-time,localized-space”operations to enhance energy savings.It includes a discussion on the structural design of the device and experimental analysis of its local environmental control and intermittent operation.The design incorporates a convective heat exchanger and radiant panel embedded in a height-adjustable desktop.Experimental results showed that the combination of the radiant panel and air outlet beneath the desktop accumulates heat in this area during heating,creating a“cool head,warm feet”thermal comfort effect.The maximum vertical temperature difference was 0.7℃ in radiation mode.For intermittent operation,the temperature response matching coefficient(TRMC)of the proposed terminal was 3.4 times that of floor heating and 2.1 times that of fan coil units,indicating superior performance.Besides,this novel terminal provides effective thermal comfort in both sitting and standing positions,offering potential energy savings in open-plan offices.By extending the room temperature setpoint to 16–18℃ in winter,the terminal can reduce energy consumption by 3.64%–12.52%.These findings provide a reference for personalized environmental control systems and intermittent heating strategies.
基金Supported by the National Natural Science Foundation of China(32072352)。
文摘To improve heating uniformity and anthocyanin content of the blueberry pulp under microwave heating,the intermittent variable power microwave heating technology was introduced in the study.The effects of technology parameters in terms of high microwave intensity heating time,intermittent time,low microwave intensity and low microwave intensity heating time on the blueberry pulp quality parameters(heating uniformity,average moisture content,the highest temperature and anthocyanin content)were investigated by using the response surface method.The results showed that the longer heating time under different microwave intensities resulted in the poorer heating uniformity.The intermittent stage promoted heat and mass transfer within the pulp and reduced the temperature difference and moisture gradient within the pulp,which enhanced desired uniformity of temperature and moisture distribution before entering the low microwave intensity heating stage.Therefore,the longer the intermittent time,the greater the heating uniformity.The optimal parameters were developed as high microwave intensity of 4 W·g^(-1),high microwave intensity heating time of 9.86 min,intermittent time of 10 min,low microwave intensity of 2.2 W·g^(-1)and low microwave intensity heating time of 6 min.This research might provide guidance for microwave heating berry fruits.
