A TOPSIS optimization for the indoor thermal environment through oscillating airflow generated from a cassette split type air conditioner

2020 ◽  
pp. 1420326X2093930
Author(s):  
Yunqing Fan
Keyword(s):  
Thermal Performance ◽  
Cfd Simulation ◽  
Control Method ◽  
Thermal Environment ◽  
Vertical Section ◽  
Thermal Preference ◽  
Air Conditioner ◽  
Indoor Thermal Environment ◽  
Swing Angle ◽  
The Impact

This study evaluates the feasibility of a control method, ‘the Technique for Order of Preference by Similarity to Ideal Solution’ (TOPSIS) for the optimization of the subzone thermal environment by optimizing the oscillating airflow generated from a cassette split type air conditioner. To address the quasi-dynamic thermal comfort problems, various operation swinging angles of the louvre in the supply opening of an air conditioner and swinging periods were investigated by computational fluid dynamics (CFD) simulation. The impact of air supply control strategies (louvres movement) on the indoor thermal environment was evaluated by multi-criteria operation under quasi-dynamic conditions. The operation parameters were shown to have significantly improved the deviation in thermal uniformity by 16.5% and thermal preference by 7.6%. A 40 s swing period and wider swing angles for the operation of the inner louvre would satisfy the thermal uniformity rather than other alternatives. A shorter swing period <20 s is insufficient to allow perfect airflow mixing at the vertical section. For individual target mode such as the room corner, the thermal performance is more sensitive to the swing angle than the swing period; by increasing the swing angle to ±60° to enhance thermal preference, a 24.1% increase in the overall thermal performance would be achieved.

Study on the Thermal Performance of the Vernacular Dwellings in Wei-He Plain of Shaanxi Province

2012 ◽  
Vol 476-478 ◽  
pp. 1589-1595
Author(s):  
Yi Ping Zhu ◽  
Xi Liao ◽  
Shu Yun Wu ◽  
Jing Luo ◽  
Yuan Jiang ◽  
...  
Keyword(s):  
Energy Saving ◽  
Thermal Insulation ◽  
Thermal Performance ◽  
Thermal Environment ◽  
Local Area ◽  
Shaanxi Province ◽  
Indoor Thermal Environment ◽  
Questionnaire Surveys

Based on indoor thermal environment test and questionnaire surveys, the paper studies on thermal insulation capacity and indoor thermal environment of the vernacular dwellings in Wei-he Plain of Shaanxi Province, China, and analyses their heating methods and application status. Besides, the popularity of sustainable techniques in local area has been evaluated and summarized. Moreover, the paper discusses the present problems in local indoor thermal environment and energy-saving status.

scholarly journals The Thermal Performance of Traditional Residential Buildings in Kathmandu Valley

2014 ◽  
Vol 10 (1) ◽  
pp. 172-183 ◽  
Author(s):  
Sushil B. Bajracharya
Keyword(s):  
Thermal Performance ◽  
Field Data ◽  
Thermal Environment ◽  
Residential Buildings ◽  
Residential Building ◽  
Kathmandu Valley ◽  
Indoor Thermal Environment ◽  
Outdoor Thermal Environment ◽  
Different Seasons ◽  
Better Than

This paper seeks to investigate into the aspects of thermal performance of traditional residential buildings in traditional settlements of Kathmandu valley. This study proceeds to analyze the detailed field data collected, with a view to identify the indoor thermal environment with respect to outdoor thermal environment in different seasons. This paper also compares the thermal performance of traditional buildings with modern residential buildings of traditional settlements of the valley. There is a regression analysis to obtain information about the thermal environment of different traditional and modern residential buildings with different conditions. The paper concludes that, thermal performance of traditional residential building, adapted in various ways to the changing thermal regime for thermal comfort is better than that of contemporary buildings.DOI: http://dx.doi.org/10.3126/jie.v10i1.10898Journal of the Institute of Engineering, Vol. 10, No. 1, 2014,  pp. 172–183

scholarly journals Influence of Lawns on the Summer Thermal Environment and Microclimate of Heritage Sites: A Case Study of Fuling Mausoleum, China

2020 ◽  
Author(s):  
Xiaoyu Wang ◽  
Peng Liu ◽  
Gongwen Xu
Keyword(s):  
Cfd Simulation ◽  
Simulation Analysis ◽  
Thermal Environment ◽  
Measurement Data ◽  
Ground Temperature ◽  
Rapid Urbanization ◽  
Actual Measurement ◽  
Heritage Sites ◽  
Human Thermal Comfort ◽  
The Impact

Abstract The thermal environment and microclimate of heritage sites has been severely impacted by rapid urbanization. This study collected various meteorological measurement data as a reference for computational fluid dynamics (CFD) simulation settings. Then CFD was applied to simulate the impact of lawns on the thermal environment and microclimate of Fuling Mausoleum. We found that lawns and soil can cool the air through evaporation, and thus have a specific cooling effect on the bricked ground. After lawns were planted, the bricked ground temperature decreased by 1.56–17.54°C than that before lawns were planted at 14:00, a decrease of 2.68%–24.20%. Under normal circumstances, when the wind speed or relative humidity increased, the ground temperature dropped. Greenbelt vegetation can adjust the microclimate and human thermal comfort indicators. The consistency of the difference between the actual measurement and the CFD simulation results shows that CFD simulation can thus accurately reflect the internal temperature field distribution if the selection of simulation parameters is reasonable. Theoretical calculation and analysis, experimental measurement research, and modern computer simulation analysis methods applied together constitute a complete system for studying modern physical environmental problems and can provide reliable and economic results.

Mathematical and experimental analysis of the thermal effectiveness of an oscillating jet with side-to-side swing louvers in a cassette split type air conditioner

2019 ◽  
Vol 29 (2) ◽  
pp. 240-254 ◽  
Author(s):  
Yunqing Fan
Keyword(s):  
Thermal Environment ◽  
Thermal Sensation ◽  
Control Strategies ◽  
Heating Time ◽  
Air Conditioner ◽  
Beta Distributions ◽  
Air Supply ◽  
The Face ◽  
Heating Mode ◽  
The Impact

The impact of air supply control strategies (louvers movement) on indoor thermal environment were evaluated in this study. The temperature uniformity was evaluated by: (i) the air distribution performance index (ADPI) to determine the air diffusion performance in heating mode; (ii) the air draught rate (DR%) on the face to determine the local discomfort due to cold draught; (iii) the mathematically determined vertical temperature stratification in a room with Beta distributions. A comparison of the conventional type with three different oscillating type airflows (louvers swing angle ±20°, ±40° and ±60°) were experimentally analysed to determine appropriate air supply control strategies. The results indicated that Beta distributions could capture the overall trend of the oscillating airflow, to establish the acceptable thermal uniformity and higher thermal effectiveness. The oscillating airflow as generated by the side-to-side swing type delivery louvers mounted inside a cassette split type air conditioner could shorten heating time by 20% to attain room temperature from 9°C. The data reveal that oscillating airflow can provide a better thermal sensation to feeling warm in the heating mode at both ankle and neck level. The ADPI is approximately 85% in the occupied zone. The actual draught rates on the face ranged 0–35%.

scholarly journals Optimal Control Method for HVAC Systems in Offices with a Control Algorithm Based on Thermal Environment

Buildings ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 95 ◽  
Author(s):  
Sung-Kyung Kim ◽  
Won-Hwa Hong ◽  
Jung-Ha Hwang ◽  
Myung-Sup Jung ◽  
Yong-Seo Park
Keyword(s):  
Optimal Control ◽  
Energy Consumption ◽  
Control Method ◽  
Thermal Environment ◽  
Hvac Systems ◽  
Control Algorithms ◽  
Total Energy Consumption ◽  
Indoor Thermal Environment ◽  
Optimal Control Method ◽  
Temperature And Humidity

This study examined a method to reduce energy consumption in office buildings. Correspondingly, an optimal control method was proposed for heating, ventilation, and air conditioning (HVAC) systems via two control algorithms that considered the indoor thermal environment. The control algorithms were developed by considering temperature and humidity as the factors of the indoor thermal environment that influence the control of HVAC systems and the predicted mean vote comfort ranges. Furthermore, an experiment was performed using office equipment that incorporated the two control algorithms for HVAC systems, and the correlation between changes in the thermal environment within the office and the occupant’s comfort levels was estimated via an actual survey. The results demonstrated that the proposed control method for HVAC systems, which considered the comfort ranges of temperature and humidity and the thermal adaptation capability, can efficiently maintain the occupant’s comfort with lower energy usage compared with conventional HVAC systems. Thus, the use of the control method contributes to the reduction of total energy consumption in buildings with HVAC systems.

scholarly journals Influence of grass lawns on the summer thermal environment and microclimate of heritage sites: a case study of Fuling mausoleum, China

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Xiaoyu Wang ◽  
Peng Liu ◽  
Gongwen Xu
Keyword(s):  
Cfd Simulation ◽  
Simulation Analysis ◽  
Thermal Environment ◽  
Measurement Data ◽  
Ground Temperature ◽  
Rapid Urbanization ◽  
Actual Measurement ◽  
Heritage Sites ◽  
Human Thermal Comfort ◽  
The Impact

AbstractThe thermal environment and microclimate of heritage sites has been severely impacted by rapid urbanization. This study collected various meteorological measurement data as a reference for computational fluid dynamics (CFD) simulation settings. Then CFD was applied to simulate the impact of lawns on the thermal environment and microclimate of Fuling Mausoleum. We found that lawns and soil can cool the air through evaporation, and thus have a specific cooling effect on the bricked ground. Simulations with the lawns, the bricked ground temperature decreased by 1.56–17.54 °C than that simulations without the lawns at 14:00, a decrease of 2.68%–24.20%. Under normal circumstances, when the wind speed or relative humidity increased, the ground temperature dropped. Greenbelt vegetation can adjust the microclimate and human thermal comfort indicators. The consistency of the difference between the actual measurement and the CFD simulation results shows that CFD simulation can thus accurately reflect the internal temperature field distribution if the selection of simulation parameters is reasonable. Theoretical calculation and analysis, experimental measurement research, and modern computer simulation analysis methods applied together constitute a complete system for studying modern physical environmental problems and can provide reliable and economic results.

scholarly journals Research on Indoor Thermal Comfort and Age of Air in Qilou Street Shop under Mechanical Ventilation Scheme: A Case Study of Nanning Traditional Block in Southern China

2021 ◽  
Vol 13 (7) ◽  
pp. 4037
Author(s):  
Xianfeng Huang ◽  
Chen Qu
Keyword(s):  
Mechanical Ventilation ◽  
Air Quality ◽  
Thermal Comfort ◽  
Thermal Environment ◽  
Southern China ◽  
Air Conditioner ◽  
Indoor Thermal Environment ◽  
Indoor Thermal Comfort ◽  
Circulation Mode ◽  
Ventilation Scheme

In hot summers, air conditioning (AC) and mechanical ventilation (such as fans) are used as cooling modes that strongly influence the resultant indoor environment, like thermal comfort and air quality in the shops of a Nanning arcade street (qilou). The air circulation mode in shops greatly affects the indoor thermal environment and level of air freshness. The approaches for effectively improving the indoor thermal comfort and air quality are developed in qilou street shops with air-conditioner in a humid and hot region in southern China. Consequently, the purpose of this study is to assess different ventilation schemes in order to identify the best one. By using two indices, i.e., the predicted mean vote (PMV) and the age of air (AoA), in situ measurement and numerical simulation are conducted to investigate humans’ thermal comfort in extreme summer. Then, the indoor thermal comfort and AoA levels in summer under three different ventilation schemes (upper-inlet–upper-outlet, upper-inlet–bottom-outlet, and side-inlet–side-outlet) are comparatively analyzed through numerical computations of the indoor thermal environment. The results show that the upper-inlet–upper-outlet mode of the AC ventilation scheme led to the creation of a favorable air quality and comfortable thermal environment inside the shop, which will help designers understand the influence of the ventilation scheme on the indoor thermal comfort and health environment.

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