Xiaojun Dong
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Xiaojun Dong has a total of 7 co-authors. Here are the top co-authors by number of shared publications:
- Tianwei Lai
State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, China
2 shared publications - Yu Hou
MOE Key Laboratory of Cryogenic Technology and Equipment, Xi'an Jiaotong University 1 , Xi'an 710049
2 shared publications - Mingchen Qiang
School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China
1 shared publication - Shaohang Yan
School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China
1 shared publication - Xue Liu
School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China
1 shared publication - Ze Zhang
State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China
1 shared publication
Latest Publications
- Open Access
- 15 April 2022
- Published by MDPI AG in Applied Sciences
- Vol. 12 (8) , 4025
Experimental Study on Frost Crystal Morphologies and Frosting Characteristics under Different Working Pressures
Frost usually grows on the cooling surface of heat transfer equipment, which often operates under different working pressures. In such conditions, one of the fundamental influencing factors of frosting, the diffusion coefficient of water vapor around the cooling surface, is different from that in the normal atmosphere pressure. In order to investigate the pressure effect on frosting, a test rig for frosting visualization is designed. The role of working pressure around the cooling surface on the frost crystal morphologies and frost layer characteristics is evaluated under different air parameters and temperatures of cooling surface. The vertical growth and lateral distribution of frost crystals are strongly related to working pressure around the cooling surface. More frost crystal morphologies and faster growth rate of frost layer are presented at a lower pressure. The frost thickness, frost accumulation and density reduce with higher pressure. The dimensionless correlation of frost thickness is proposed considering working pressure around the cooling surface, humid air parameters, and temperature of cooling surface.
- 15 April 2022
- Published by MDPI AG in Applied Sciences
- Vol. 12 (8) , 4025
Open AccessExperimental Study on Frost Crystal Morphologies and Frosting Characteristics under Different Working Pressures
Frost usually grows on the cooling surface of heat transfer equipment, which often operates under different working pressures. In such conditions, one of the fundamental influencing factors of frosting, the diffusion coefficient of water vapor around the cooling surface, is different from that in the normal atmosphere pressure. In order to investigate the pressure effect on frosting, a test rig for frosting visualization is designed. The role of working pressure around the cooling surface on the frost crystal morphologies and frost layer characteristics is evaluated under different air parameters and temperatures of cooling surface. The vertical growth and lateral distribution of frost crystals are strongly related to working pressure around the cooling surface. More frost crystal morphologies and faster growth rate of frost layer are presented at a lower pressure. The frost thickness, frost accumulation and density reduce with higher pressure. The dimensionless correlation of frost thickness is proposed considering working pressure around the cooling surface, humid air parameters, and temperature of cooling surface.
- Open Access
Influence of Refrigerant Charge Amount and EEV Opening on the Performance of a Transcritical CO2 Heat Pump Water Heater
Besides compressor rotary speed and parameters of water flowing through gas cooler and evaporator, refrigerant charge amount and electronic expansion valve (EEV) opening are two important parameters that have significant effects on the performance of a transcritical CO2 heat pump system. In this study, the effects of refrigerant charge amount on the performance of a transcritical CO2 heat pump water heater were investigated experimentally at different EEV openings. An optimal coefficient of performance (COP) was found that corresponded to a specific refrigerant charge and a specific EEV opening. Based on the experiment, the COP peaked at charge of 1.8 kg when EEV opening was 40% of full opening. The heating capacity and the COP increased at first, reached peaks and then decreased with increase of charge amount. The COP decreased 14.95% as the CO2 charge amount was reduced by 22.2% from the optimal charge at 50% EEV opening. As EEV opening varied from 40% to 60% at the same charge amount, the heating capacity decreased more than 30%.
Open AccessInfluence of Refrigerant Charge Amount and EEV Opening on the Performance of a Transcritical CO2 Heat Pump Water Heater
Besides compressor rotary speed and parameters of water flowing through gas cooler and evaporator, refrigerant charge amount and electronic expansion valve (EEV) opening are two important parameters that have significant effects on the performance of a transcritical CO2 heat pump system. In this study, the effects of refrigerant charge amount on the performance of a transcritical CO2 heat pump water heater were investigated experimentally at different EEV openings. An optimal coefficient of performance (COP) was found that corresponded to a specific refrigerant charge and a specific EEV opening. Based on the experiment, the COP peaked at charge of 1.8 kg when EEV opening was 40% of full opening. The heating capacity and the COP increased at first, reached peaks and then decreased with increase of charge amount. The COP decreased 14.95% as the CO2 charge amount was reduced by 22.2% from the optimal charge at 50% EEV opening. As EEV opening varied from 40% to 60% at the same charge amount, the heating capacity decreased more than 30%.