Quantitative investigations on setting parameters of air conditioning (air-supply speed and temperature) in ventilated cooling rooms

2019 ◽  
Vol 30 (1) ◽  
pp. 99-113 ◽  
Author(s):  
Haofu Chen ◽  
Zhuangbo Feng ◽  
Shi-Jie Cao
Keyword(s):  
Thermal Comfort ◽  
Air Conditioning ◽  
Thermal Environment ◽  
Inertial Force ◽  
Index Formula ◽  
Design Parameters ◽  
Dimensionless Number ◽  
Indoor Thermal Environment ◽  
Indoor Thermal Comfort ◽  
Air Supply

Rational and scientific design of indoor air conditioning is essential. In the design of Heating, Ventilating and Air Conditioning system, air-supply speed (ventilation rate) and air-supply temperature are the two most important parameters. In the current study, numerical simulations and experimental measurements were adopted to investigate the influences of ventilation mode, air-supply velocity and air-supply temperature on indoor thermal comfort as well as building energy consumption in summer. Different ventilation modes (up supply and down exit, ceiling supply and ceiling exit) were considered in modelling. Based on the simulation and experimental results, dimensionless index [Formula: see text] is proposed, which represents the ratio of buoyancy weighting force to inertial force. This index can be used as a pre-evaluation index of indoor thermal comfort in preliminary design of air conditioning. It is an indicator to judge the working conditions in cooling-ventilated rooms. When [Formula: see text], the settlement and diffusion effects of indoor airflow reach a good level, which means that the parameter setting could provide a comfortable indoor thermal environment. The dimensionless number [Formula: see text] is a theoretically based tool in the pre-evaluation of indoor thermal environment, providing guidance for setting of ventilation design parameters.

scholarly journals Energy-saving potential of intermittent heating system: Influence of composite phase change wall and optimization strategy

2020 ◽  
pp. 014459872096921
Author(s):  
Yanru Li ◽  
Enshen Long ◽  
Lili Zhang ◽  
Xiangyu Dong ◽  
Suo Wang
Keyword(s):  
Energy Consumption ◽  
Thermal Comfort ◽  
Phase Change ◽  
Air Temperature ◽  
Indoor Air ◽  
Thermal Environment ◽  
Optimization Strategy ◽  
Indoor Thermal Environment ◽  
Indoor Thermal Comfort ◽  
Intermittent Heating

In the Yangtze River zone of China, the heating operation in buildings is mainly part-time and part-space, which could affect the indoor thermal comfort while making the thermal process of building envelope different. This paper proposed to integrate phase change material (PCM) to building walls to increase the indoor thermal comfort and attenuate the temperature fluctuations during intermittent heating. The aim of this study is to investigate the influence of this kind of composite phase change wall (composite-PCW) on the indoor thermal environment and energy consumption of intermittent heating, and further develop an optimization strategy of intermittent heating operation by using EnergyPlus simulation. Results show that the indoor air temperature of the building with the composite-PCW was 2–3°C higher than the building with the reference wall (normal foamed concrete wall) during the heating-off process. Moreover, the indoor air temperature was higher than 18°C and the mean radiation temperature was above 20°C in the first 1 h after stopping heating. Under the optimized operation condition of turning off the heating device 1 h in advance, the heat release process of the composite-PCW to the indoor environment could maintain the indoor thermal environment within the comfortable range effectively. The composite-PCW could decrease 4.74% of the yearly heating energy consumption compared with the reference wall. The optimization described can provide useful information and guidance for the energy saving of intermittently heated buildings.

scholarly journals Importance of Behavioral Adjustments for Adaptive Thermal Comfort in a Condominium with HEMS System

2020 ◽  
Vol 15 (3) ◽  
pp. 163-170
Author(s):  
Rajan KC ◽  
Hom Bahadur Rijal ◽  
Masanori Shukuya ◽  
Kazui Yoshida
Keyword(s):  
Thermal Comfort ◽  
Air Temperature ◽  
Energy Use ◽  
Thermal Environment ◽  
Residential Buildings ◽  
Outdoor Environment ◽  
Adaptive Behaviors ◽  
Outdoor Air ◽  
Indoor Thermal Environment ◽  
Indoor Thermal Comfort

The energy use in residential dwellings has been increasing due to increasing use of modern electric appliances to make the lifestyle easier, entertaining and better. One of the major purposes of indoor energy use is for improving indoor thermal environment for adjusting thermal comfort. Along with the use of passive means like the use of mechanical devices, the occupants in any dwellings use active means such as the use of natural ventilation, window opening, and clothing adjustment. In fact, the use of active means when the outdoor environment is good enough might be more suitable to improve indoor thermal environment than the use of mechanical air conditioning units, which necessarily require electricity. Therefore, the people in developing countries like Nepal need to understand to what extent the occupants can use active means to manage their own indoor thermal comfort. The use of active means during good outdoor environment might be an effective way to manage increasing energy demand in the future. We have made a field survey on the occupants’ adaptive behaviors for thermal comfort in a Japanese condominium equipped with Home Energy Management System (HEMS). Online questionnaire survey was conducted in a condominium with 356 families from November 2015 to October 2016 to understand the occupants’ behaviors. The number of 17036 votes from 39 families was collected. The indoor air temperature, relative humidity and illuminance were measured at the interval of 2-10 minutes to know indoor thermal environmental conditions. The occupants were found using different active behaviors for thermal comfort adjustments even in rather harsh summer and winter. Around 80% of the occupants surveyed opened windows when the outdoor air temperature was 30⁰C in free running (FR) mode and the clothing insulation was 0.93 clo when the outdoor air temperature was 0⁰C. The result showed that the use of mechanical heating and cooling was not necessarily the first priority to improve indoor thermal environment. Our result along with other results in residential buildings showed that the adaptive behaviors of the occupants are one of the primary ways to adjust indoor thermal comfort. This fact is important in enhancing the energy saving building design.

Indoor Thermal Environment Test and Investigation Analysis—Based on Newly-Built Residential Houses in Daping Village, Sichuan Province

2011 ◽  
Vol 368-373 ◽  
pp. 3667-3671
Author(s):  
Hui Cheng ◽  
Jia Ping Liu ◽  
Da Long Liu ◽  
Fang Wei Tang ◽  
Yun Gang An
Keyword(s):  
Thermal Comfort ◽  
Thermal Environment ◽  
Building Design ◽  
Sichuan Province ◽  
Objective Test ◽  
Environment Design ◽  
Residential Housing ◽  
Indoor Thermal Environment ◽  
Indoor Thermal Comfort ◽  
Housing Environment

Based on the recognition of original defective residential housing environment in Daping village, constructional measures were improved and updated. Objective test and subjective investigation on indoor thermal comfort were carried out and analyzed in the typically new and old residential houses to propose measures for further improvements. This paper aims to summarize experience and deficiencies in aspects of indoor thermal environment design and to provide reference to building design after disasters in future.

Indoor Thermal Environment Simulation of Xi'an Residential Building in Summer

2012 ◽  
Vol 512-515 ◽  
pp. 2882-2886
Author(s):  
Shi Jie Wu ◽  
Zeng Feng Yan
Keyword(s):  
Thermal Comfort ◽  
Natural Ventilation ◽  
Thermal Environment ◽  
Residential Building ◽  
Indoor Thermal Environment ◽  
Indoor Thermal Comfort ◽  
Energy Plus ◽  
Environment Simulation ◽  
Indoor Air Flow ◽  
Night Ventilation

Natural ventilation is an important role to improve the residential building indoor thermal environment in summer. This paper use Energy Plus to simulate indoor thermal environment and use CFD to simulate indoor air flow for Xi’an residential building, analysis the influence that different ventilation mode for indoor thermal environment factors. Then with the simulated result of PMV-PPD value to estimate indoor thermal comfort. Proved night ventilation is necessary in residential building in Xi’an and effectiveness to improve indoor thermal comfort.

Indoor Thermal Environment Research of Air Conditioning Office with Air from Window Gap

2013 ◽  
Vol 860-863 ◽  
pp. 1660-1665
Author(s):  
Ze Hua Liu ◽  
Yan Liao ◽  
Hao Ping Yu
Keyword(s):  
Numerical Simulation ◽  
Air Conditioning ◽  
Thermal Environment ◽  
Local Area ◽  
Indoor Thermal Environment ◽  
Air Infiltration ◽  
Air Supply ◽  
Field Velocity ◽  
Average Relative Humidity ◽  
Air Speed

The paper presents a numerical simulation study of indoor thermal environment of an air conditioning office in winter in Hengyang. Considering the effect of air infiltration from window gap, the distribution of indoor temperature field, velocity field and humidity field can be obtained when air supply angle is 45° down to the horizontal direction. Compared with simulation which air infiltration is ignored, the results show that average temperature of air conditioning area reduces 0.6 °C in Y = 1.1 m section. Air velocity is larger in Y = 1.1 m air conditioning zone. The air speed is greater than 0.2 m/s in local area, a sense blowing. Average relative humidity is larger in Y = 1.1 m air conditioning area. The research indicates that air infiltration can not be allowed to be neglected in numerical simulation.

Comparative Evaluation of Indoor Thermal Comfort for Green and Conventional Office Buildings

Solar Energy ◽  
2004 ◽  
Author(s):  
Alex Nunez ◽  
Moncef Krarti
Keyword(s):  
Comparative Analysis ◽  
Thermal Comfort ◽  
Thermal Environment ◽  
Green Building ◽  
Mean Value ◽  
Building Construction ◽  
Office Buildings ◽  
Indoor Thermal Environment ◽  
Indoor Thermal Comfort ◽  
Construction Methods

A comparative analysis was conducted between two office buildings, one constructed using green design and the other erected using traditional building construction methods. As part of the analysis, thermal comfort indicators (using the Predicted Mean Value of Fanger model) were monitored by recording equivalent temperature, air temperature, and relative humidity at each site. The study tests whether office buildings constructed using different design approaches have significantly different indoor thermal environment. The results of the comparative analysis indicate that the green building provides better thermal comfort than the conventional building.

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.

The Study of Indoor Thermal Environment Characteristics of Office Building Effected by Stratum Ventilation

2014 ◽  
Vol 556-562 ◽  
pp. 803-806
Author(s):  
Ze Qin Liu ◽  
Zhen Jun Zuo ◽  
Tai Shun Liu
Keyword(s):  
Thermal Comfort ◽  
Thermal Stratification ◽  
Thermal Environment ◽  
Vertical Direction ◽  
Ventilation Rate ◽  
Office Building ◽  
Breathing Zone ◽  
Indoor Thermal Environment ◽  
Human Thermal Comfort ◽  
Air Supply

A typical office building with stratum ventilation as the research object was studied in this paper. CFX Fluid Computation software was used to numerical simulate the characteristics of indoor thermal environment effected by air speeds under 19°C supply air temperature and 8 ventilation rate. The numerical simulate results showed that, the obvious thermal stratification occurred in the vertical direction. Such thermal stratification met the demands of building energy conservation and the human thermal comfort. In this paper, the velocity coefficient and the temperature coefficient were used to evaluate thermal comfort. From the results of the numerical simulation, it could be seen that when the supply air speeds were controlled between 0.5m/s to 0.9m/s, the thermal comfort, as well as the air supply efficiency in the human activity area was relative satisfactory. With the constant fresh air ventilated to the breathing zone, the air quality could be improved.

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