The Experimental Study on the Effects of Supply Air Angle on Indoor Thermal Environment

Numerical Simulation of Indoor Thermal Environment Effected by Air Supply Temperature and Grille Angle on Stratum Ventilation in a Typical Office

Experimental and numerical analysis of air temperature uniformity in occupied zone under stratum ventilation for heating mode

Numerical Simulation of Energy Utilization Coefficient Influenced by Desktop Personalized Ventilation Modes

Experimental Study on the effects of layered air supply angle and air supply temperature on indoor environment

How green building rating systems affect indoor thermal comfort environments design

Air curtains is promising in reducing the short-range infection risk in hospitals. To quantitatively evaluate its performance, this paper explores air curtains equipped on normal consulting desk to avoid doctor’s direct exposure to the patient exhaled pollutants. A numerical investigation is conducted to evaluate the effects of supply air velocity and angle on cutting off performance. Simulation results show that the average mass fraction of exhaled pollutants decreases significantly (70%–90%) in the consulting ward, indicating satisfying performance of air curtains. Increasing supply air velocity is demonstrated to be conducive in forming full air curtains, whereas an excessively high supply air velocity may be of adverse effects by entraining exhaled flow. Besides, the supply air angle is also critical due to its coupling with supply air velocity. It is found that larger angle (0°–40°) is better where velocity is less than 3 m/s, otherwise a small angle (20°) is preferable where velocity is larger than 3 m/s. Exhaled flow could be well suppressed at the supply air angle 20° but moves over air curtains at 40°. This study can provide effective and intuitive guidance in applying air curtains in consulting wards.Electronic Supplementary Material (ESM)Supplementary material is available in the online version of this article at 10.1007/s12273-020-0649-7. The ESM files include the animation of patient exhaled droplets from the droplet birth at 0 s to 5 s under the supply air angle 0°, 20°, 40°, at supply air velocity 3 m/s.

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.

Based upon Fanger's thermal comfort model, the numerical simulation was adopted to predict air flow pattern and human thermal comfort environment. The numerical modeling was used to research indoor thermal comfort environment on different air distributions in summer, numerical simulation results provide indoor velocity, temperature and PMV index distributions. Then, a laboratory experimental measurement at indoor thermal comfort environment in a full-scale test chamber was conducted by Thermal Comfort Monitoring Station to validate the simulation results. Research conclusions provide reference basis for the improvement of indoor thermal comfort environment, the design and energy-saving control of comfort air-conditioning systems.

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%.

Indoor thermal environment in a rural dwelling heated by air-source heat pump air-conditioner

Personalized kitchen air supply for reducing individual thermal discomfort and cooking pollution intake

The characteristics of a stratified air-conditioning system, only maintaining task zone's certain air temperature and air velocity of large space building, are studied in an airport terminal building. The indoor thermal environment is discussed by means of Computational Fluid Dynamics (CFD) software under various conditions of supply air temperature, velocity, height and angle of incidence. The mean velocity, mean temperature, non-uniform coefficient of velocity distribution, non-uniform coefficient of temperature distribution, air diffusion performance index are adopted as the thermal comfort indices to evaluate the air velocity and temperature fields in the occupied region. Based on the analysis of heat load in the top zone, the opening where it locates and its sizes is confirmed. The primary design schemes are modified and further simulations are undertaken for modified flow fields in terms of above evaluation indices. The upper opening is disadvantageous for saving energy in summer. CFD technology that predicts airflow distribution is an efficient tool to evaluate the implementation of different supply air parameters in the building and to assist in decision making concerning building structure and passenger's thermal comfort problems.

A wall hanging air-conditioning office was simulated on three different air supply angle and three different air supply velocity by the AIRPAK .Based on the velocity fields, temperature fields, PMV-PPD obtained, analysis indoor thermal comfort. The result shows obvious difference of air distribution and great effect of indoor thermal under different air supply angle and different air supply velocity. By comprehensive comparison, the best air supply condition is the one of 75° downward, 3.0m/s.

With the rapid development of the national economy, increasing attention has been given to the living environment in rural areas, especially indoor thermal and wind environments. This study conducted on-site measurements and questionnaire surveys during winter in the indoor environment of five villages in northeastern Sichuan. Eighty-nine traditional residences were selected to investigate their fundamental characteristics, indoor thermal environment, humidity conditions, and comfort levels. Questionnaires and comparative experiments were also conducted with natives and locals. This combination of objective data and subjective feedback provides a comprehensive perspective for assessing the indoor thermal environment. The results showed that when expressed as neutral temperature and humidity, the temperature difference was 2.36 °C, with little humidity difference. Residents exhibited higher tolerance towards the local thermal and humidity environment than nonlocal volunteers, who showed greater sensitivity to it. In addition, residents had a Predicted Mean Vote (PMV) value of −0.69 and a heat acceptance value of −1.78, while non-local volunteers had a PMV value of −0.76 and a heat acceptance value of −1.32. A detailed evaluation and analysis of the relationship between the indoor thermal environment and human comfort of local residential houses was carried out, providing technical guidance for energy conservation and thermal insulation of local buildings.

Research on a new optimization method for airflow organization in breeding air conditioning with perforated ceiling ventilation