scholarly journals Effects of Supply Parameters of Stratum Ventilation on Energy Utilization Efficiency and Indoor Thermal Comfort: A Computational Approach

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Lina Zhang ◽  
Yanhui Mao ◽  
Qiu Tu ◽  
Xiaogang Wu ◽  
Lingyu Tan
Keyword(s):  
Thermal Comfort ◽  
Thermal Performance ◽  
Energy Utilization ◽  
Utilization Efficiency ◽  
Airflow Rate ◽  
Heating Condition ◽  
Indoor Thermal Comfort ◽  
Supply Angle ◽  
Air Supply ◽  
Ventilation Effectiveness

Stratum ventilation shows the significant potential on energy conservation and indoor thermal comfort under cooling applications. Yet, only limited researches focus on the thermal performance of stratum ventilation under heating condition. The heating and cooling operation characteristic of stratum ventilation is different due to the distinct airflow characteristics. Therefore, this paper investigated the parameters that affect energy utilization efficiency and indoor thermal comfort under heating condition served by stratum ventilation via CFD simulations approach. The supply air parameters included temperature, airflow rate, angle, and return air outlet positions. The evaluation indicators adopt ventilation effectiveness and effective draft temperature (EDT) for assessing the energy utilization efficiency and indoor thermal comfort served by stratum ventilation under heating condition. The results demonstrated that, under the heating mode of stratum ventilation, different effects on the thermal performance were made by the mentioned parameters. The ventilation effectiveness was higher when the air supply temperature is 26°C, airflow rate is 7 air change per hour (ACH), and the air supply angle is 45°. The EDT range of the occupied zone is closest to zero K when the air supply temperature is 28°C, airflow rate is 12 (ACH), and the air supply angle is 60°. The related conclusions obtained from this study provide the theoretical basis for the stratum ventilation design and promote its heating application.

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.

Thermal Comfort Study of Wall Hanging Air-Conditioning Office in Summer

2014 ◽  
Vol 1008-1009 ◽  
pp. 1088-1091
Author(s):  
Lan Xia Guo ◽  
Xiao Yong Peng ◽  
Jian Xiang Liu ◽  
Xu Sheng Chai ◽  
Jing Jing Liang ◽  
...  
Keyword(s):  
Thermal Comfort ◽  
Indoor Air ◽  
Mean Value ◽  
Vital Role ◽  
Velocity Fields ◽  
Temperature Fields ◽  
Air Distribution ◽  
Supply Angle ◽  
Air Supply ◽  
Supply Velocity

Airpak was applied to numerically simulate the air distribution under the same air supply temperature ,different air supply velocity (3.6m/s、2.7m/s and 1.8m/s ) and air supply angle (+15°、-45° and-75°) , and evaluate thermal comfort by Comparative analysis velocity fields, temperature fields, PMV—PPD. The results show that different air supply velocity and air supply angle have a significant impact on indoor air distribution under the same air supply temperature. Air supply angle Plays a vital role in pattern and distribution of indoor flow field,air supply velocity mainly effect the magnitude of indoor velocity and temperature. Synthetically comparied, the model’s best supply parameters are supply velocity 2.7m/s and supply angle75°,which mean value of indoor PMV is-0.09, PPD is 8.5%.

scholarly journals On the improvement of thermal comfort in indoor spaces conditioned by split-type systems

2019 ◽  
Vol 111 ◽  
pp. 02052
Author(s):  
Silva Júnior Anastácio da ◽  
Cordeiro Mendonça Kátia ◽  
Vilain Rogério ◽  
Pereira Marcelo Luiz ◽  
Mendes Nathan
Keyword(s):  
Thermal Comfort ◽  
Low Cost ◽  
Type System ◽  
Type Systems ◽  
Cooling Capacity ◽  
Linear Regression Method ◽  
Airflow Rate ◽  
Set Point ◽  
Air Supply ◽  
Radiant Temperature

Conventional on/off-based control split-type appliances are widely used in classrooms and offices, in Brazil and in many other countries, due to their low cost and ease of installation. However, occupants often complain about thermal discomfort depending on their position within the conditioned space, especially in positions that are directly affected by the draft, since those equipment provide high cold air velocities as a result of their high cooling capacity relatively to their air supply area. In order to improve the indoor thermal comfort in spaces conditioned by this kind of system, a simplified empirical model for controlling both the supply airflow and the temperature set-point is proposed in this work. In view of that, the comfort conditions in an occupied classroom were experimentally evaluated according to ISO 7730 Standard, which defines the thermal satisfaction in occupied environments based on the PMV index. Specifically, the speed, temperature and relative humidity of the air and the mean radiant temperature of the room were measured at 8 positions within the air conditioned space, for the three original air flows (high, medium and low) of a 10.5-kW cooling capacity appliance and three set-point temperatures (23, 24 and 25 °C). The simplified model, correlating thermal comfort and the variables that could be directly controlled by the split-type system (airflow rate and temperature), was obtained by adjusting several curves from 72 measuring assemblies (8 measuring points, 3 set-point temperatures and 3 supply airflows). The correlation that best represents the distribution of thermal comfort throughout the conditioned environment was provided by the non-linear regression method of Levenberg-Marquardt.

scholarly journals Influence of different air supply parameters on indoor thermal comfort of upper air supply room

2021 ◽  
Vol 791 (1) ◽  
pp. 012197
Author(s):  
Pei Xiang ◽  
Min Dong ◽  
Nengmeng Huo ◽  
Chuanliang Xu ◽  
Fengluan Yang
Keyword(s):  
Thermal Comfort ◽  
Indoor Thermal Comfort ◽  
Air Supply

scholarly journals Numerical Research and Parametric Study on the Thermal Performance of a Vertical Earth-to-Air Heat Exchanger System

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Zhening Zhang ◽  
Jindong Sun ◽  
Zhenxing Zhang ◽  
Xinxin Jia ◽  
Yang Liu
Keyword(s):  
Heat Exchanger ◽  
Thermal Performance ◽  
Geothermal Energy ◽  
Energy Utilization ◽  
Construction Costs ◽  
System A ◽  
Air Supply ◽  
Low Energy Buildings ◽  
New Type ◽  
Condensed Water

The earth-to-air heat exchanger (EAHE) system, as a clean and efficient shallow geothermal energy application technology, has obvious effects in reducing the energy consumption of passive low-energy buildings. The traditional horizontal EAHE system is difficult to apply and popularize due to its large occupation, unfavorable shallow soil temperature, and difficulty in timely centralized discharge of condensed water. This paper proposes a new type of vertical earth-to-air heat exchanger (VEAHE) system. The VEAHE system has a number of advantages such as smaller occupation, efficient geothermal energy utilization, and centralized discharge of condensed water. In order to evaluate the influence of different parameters on the thermal performance of the VEAHE system, a mathematical model of the VEAHE system was developed. And, the data calculated by the model highly tallied with the experimental data. The results showed that laying thermal insulation layers at the outlet of risers will effectively restrain the interference of downcomers to risers. It is advisable to set thickness and length of the insulation layer at 30 mm and 3 m. Considering the compromise between thermal performance and construction costs of the VEAHE system, the length of the ducts at 30–50 m and the diameter at 150–250 mm are recommended. The air supply volume of a single shaft can reach 500–1200 m3/h as the air velocity reaches 3–7 m/s.

Numerical Simulation of Energy Saving at Different Air Supply Angles in Air-Conditioned Room

2013 ◽  
Vol 385-386 ◽  
pp. 263-267 ◽  
Author(s):  
Jun Qiang Yang ◽  
Ming Jun Li
Keyword(s):  
Energy Saving ◽  
Design Method ◽  
Energy Utilization ◽  
Small Space ◽  
Utilization Coefficient ◽  
Supply Angle ◽  
Maximum Value ◽  
Air Supply ◽  
Saving Effect ◽  
The Mathematical Model

The air-conditioned room in small space is studied by establishing the mathematical model of the air flow arrangement for energy saving. The energy saving effect is analyzed numerically at different angles under circumstance of the most common way of one-side up supply and down return. Our results show that if air supply angle is set at , the energy utilization coefficient is maximum value,and air condition reaches best energy-saving state. Our design method can be referenced valuably for the air exit design and regulating of air-conditioned room in real project.

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