The Numerical Simulation of Thermal Environment of Strawberry Greenhouse in Natural Ventilation

2014 ◽  
Vol 501-504 ◽  
pp. 2276-2281 ◽  
Author(s):  
Wei Hong Fu ◽  
Shi Jun You
Keyword(s):  
Numerical Simulation ◽  
Wind Speed ◽  
Air Temperature ◽  
Natural Ventilation ◽  
Thermal Environment ◽  
Environmental Parameters ◽  
Outdoor Air ◽  
Air Velocity ◽  
Indoor Thermal Environment ◽  
Average Temperature

The method of numerical simulation was adopted in this study to explore the size of the natural ventilation inlet opening, outdoor temperature and ambient wind speed and other environmental parameters to effect of the varied rules of thermal environment of the strawberry solar greenhouse. The variation of outdoor air temperature effected greatly to the indoor thermal environment, the average air velocity in the strawberry growing zoon within the greenhouse was rose initially and dropped tend to the steady with increasing outdoor air temperature. The average temperature in the strawberry growing zoon was decreased with increasing the outside wind speed. The average air velocity was increased gradually in the strawberry growing zoon within the greenhouse with increasing outdoor wind speed. The average velocity was reduced gradually toward to constant.

New Correlations Including Hourly Horizontal Radiation for Predicting Indoor Thermal Environment

2011 ◽  
Vol 71-78 ◽  
pp. 2671-2674
Author(s):  
Sheng Xian Wei ◽  
Shi Mei Guo ◽  
Xi Jia He
Keyword(s):  
Solar Radiation ◽  
Air Temperature ◽  
Natural Ventilation ◽  
Thermal Environment ◽  
Thermal Sensation ◽  
Environmental Parameters ◽  
Newton’S Iterative Method ◽  
Indoor Thermal Environment ◽  
One Year ◽  
Radiant Temperature

Fanger’s PMV is the most famous thermal sensation index but it is too complex to be applied in practice. Besides, the PMV index does not include the effect of horizontal solar radiation on the indoor thermal environment. In order to obtain simple and applicable correlations with consideration of solar radiation, a one-year measurement has been conducted in a naturally ventilated residential room in Qujing Normal University of Yunnan province, China. Based on collected data, PMV indices are calculated by using Newton’s iterative method. The relationships of the PMV and the environmental parameters — outdoor air temperature, indoor mean air temperature, mean radiant temperature, wind velocity, relative humidity, and hourly horizontal solar radiation — have been studied by the multivariable regression techniques. Large numbers of correlations with high correlativity have been developed in the present paper. It is convenient to use them to evaluate and predict the indoor thermal environment in the natural ventilation 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.

Influence of Surface Boundary Conditions on Architectural Indoor Thermal Environment with Air Conditioning

2012 ◽  
Vol 170-173 ◽  
pp. 2756-2759
Author(s):  
Yuan Liang
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Air Conditioning ◽  
Thermal Environment ◽  
Surface Boundary ◽  
Outdoor Air ◽  
Indoor Thermal Environment ◽  
Average Temperature ◽  
Environment Model ◽  
Surface Boundary Conditions

In order to analysis influence on indoor thermal environment with surface boundary which are the first boundary condition and the second boundary condition under the average temperature distributed hourly of the outdoor air, indoor thermal environment model of single architectural with air conditioning was established, and the indoor thermal environment was simulated by the CFD software. The results show that, there is a little influence between the two kinds of surface boundary conditions, and the two kinds of surface boundary conditions could be considered as equivalent.

Indoor Thermal Environment Studies and Comparisons of Representative Residential Buildings in Urban Village of Guangzhou during Typical Weather in Summer

2011 ◽  
Vol 374-377 ◽  
pp. 66-69
Author(s):  
Zhi Sheng Li ◽  
Jia Wen Liao ◽  
Xu Hong Liu
Keyword(s):  
Air Temperature ◽  
Natural Ventilation ◽  
Thermal Environment ◽  
Residential Buildings ◽  
Correlation Coefficients ◽  
Environment Design ◽  
Indoor Thermal Environment ◽  
Human Thermal Comfort ◽  
Urban Village ◽  
And Control

In order to improve human thermal comfort of residential buildings in urban village, the study of indoor thermal environment is necessary. Three typical selected houses in Huangpu Village were taken as an example to study. After a seven-day field measurement under the condition of natural ventilation, thermal neutral temperature and PMV indices were calculated based on the collected data. It is shown that the PMV values of the houses vary from -0.5 to 2.1, and the acceptance rate differ significantly in different houses and human activities states. The parameters including outdoor air temperature, indoor air temperature and PMV were studied through the linear regression, and the results demonstrate that their correlation coefficients are high, and their relationships have been developed. The results of this work create a precedent for the indoor thermal environment design and control of urban village buildings in China.

Investigation on Air Quality in Strawberry Greenhouse under Natural Ventilation

2014 ◽  
Vol 675-677 ◽  
pp. 382-387
Author(s):  
Wei Hong Fu ◽  
Shi Jun You
Keyword(s):  
Numerical Simulation ◽  
Temperature Field ◽  
Natural Ventilation ◽  
General Trend ◽  
Environmental Parameters ◽  
Air Velocity ◽  
Indoor Temperature ◽  
Air Inlet ◽  
Simulation And Experiment ◽  
The Impact

The effect of the air inlet and the air outlet of the strawberry greenhouse are very significant to the microclimate in greenhouse under the conditions of natural ventilation. This paper studied the numerical simulation and experiment of indoor temperature field of the strawberry greenhouse with natural ventilation in different areas of air inlet and air outlet. The impact of the natural ventilation on the microclimate of strawberry greenhouse has been explored. The results indicated that the air velocity and temperature in the air inlet effected on the temperature distribution within the greenhouse, and the temperature near the air inlet was susceptible to the outdoor environmental parameters. The general trend of the variation of the indoor temperature in the greenhouse decreased with increasing the sizes of the air inlet and the air outlet. The overall trend of temperature gradient is similar within the greenhouse.

scholarly journals NEURAL NETWORKS FOR THE SIMULATION OF MICROCLIMATIC PARAMETERS IN DAIRY HOUSES

2009 ◽  
Vol 40 (2) ◽  
pp. 45
Author(s):  
Alessandro D'Emilio ◽  
Rosari Mazzarella ◽  
Simona M.C. Porto
Keyword(s):  
Wind Speed ◽  
Air Temperature ◽  
Parametric Analysis ◽  
Natural Ventilation ◽  
Outdoor Air ◽  
Adequate Accuracy ◽  
Temperature And Humidity ◽  
Air Speed ◽  
Artificial Neural Network Ann ◽  
Range Of Values

The aim of the present paper is to study natural ventilation in a dairy house by means of a parametric analysis relating wind speed and direction to the air flows through the ridge vent of the building. This analysis was carried out by means of an artificial neural network (ANN) which capability in modelling and simulating some climatic parameters inside a dairy house has been validated using the data collected in a trial carried out during summer 2005. The results show that modelling a Generalized feed-forward Multi-Layer Perceptron ANN allowed to obtain satisfactory results in the simulation of air speed and direction and air temperature and humidity inside a dairy house, using as input the values of wind speed and direction and outdoor air temperature and humidity. The adequate accuracy in the simulation of the air motion across the ridge vent allowed to perform a parametric analysis of the ventilation, which provided the values of air speed and direction in function of a fixed range of values of wind speed and direction.

Measurement of indoor environmental parameters and analysis of the condensation phenomenon in urban utility tunnels

2022 ◽  
pp. 1420326X2110564
Author(s):  
Chuanmin Tai ◽  
Guansan Tian ◽  
Wenjun Lei
Keyword(s):  
Water Supply ◽  
Surface Temperature ◽  
Air Temperature ◽  
Natural Ventilation ◽  
Environmental Parameters ◽  
Dew Point ◽  
Control Mode ◽  
Safe Management ◽  
Environmental Test ◽  
Water Supply Pipeline

Condensation is a major issue in the safe operation of utility tunnels. To address the condensation problem, the indoor air temperature, relative humidity (RH) and surface temperature in an urban utility tunnel in Jining were continuously measured, and the condensation conditions were surveyed and analysed. The results indicated that under natural ventilation conditions, the air temperature in the comprehensive cabin varied from 23.4°C to 24.5°C, the RH fluctuated between 86.4% and 95.3%, and the corresponding air dew point temperature (DPT) remained in the range of 22.2°C–22.9°C. The surface temperature of the water supply pipeline ranged from 17.8°C to 18.5°C, which was far lower than the DPT in the tunnel, resulting in serious condensation. A water supply pipeline with an anti-condensation design was developed based on environmental test data. A 25-mm-thick rubber plastic sponge insulation layer was used to thermally insulate the water supply pipeline, preventing further dew condensation. Furthermore, mechanical ventilation had little effect on reducing the RH in the tunnel and may actually cause dew condensation; therefore, a ventilation control mode was proposed in this study. These results are expected to provide basic data for further research and reference for the safe management of utility tunnels.

Experimental and Theoretical Investigation of Performance of a Solar Chimney Model, Part I: Experimental Investigation

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Essaied M Shuia ◽  
Bashir H Arebi ◽  
Ibrahim A abuashe
Keyword(s):  
Experimental Data ◽  
Wind Speed ◽  
Solar Radiation ◽  
Air Temperature ◽  
Solar Collector ◽  
Experimental Results ◽  
Internal Diameter ◽  
Solar Chimney ◽  
Air Velocity ◽  
Collector Temperature

This paper presents the experimental data that was collected from small pilot solar chimney. The experimental data together with ambient conditions are used to evaluate the performance and study the behavior of the solar chimney; this data will be used for comparison with theoretical models in another paper [part II). The solar chimney prototype was designed and constructed at the Subrata Faculty of Engineering-Libya. The data were collected over several days of June 2011. The solar chimney system contains two main components; the solar collector and the solar chimney. The solar collector root‘ has a circular area of126 m3, the solar chimney is a PVC tube with internal diameter of 0.2 m and the total height of chimney is 9.3 m. The measurements include the intensity of solar radiation inside/outside the collector, temperature and velocity of air at the entrance of the chimney, temperature and speed of wind outside the collector, temperature of the ground inside collector al1d temperature measurements of air at speci?c points at different levels throughout the collector. Solar irradiance was found to affect the chimney temperature and subsequently affects chimney air velocity. The experimental results showed that temperature differences of (30 - 45°C) were recorded between the ambient temperature and that of air inside the chimney in the middle of the day, where the highest air temperature of 73.4°C was recorded at the entrance of the solar chimney. The maximum air velocity of 3.6 m/s was recorded inside the solar chimney at noon on 9 June. Wind speed outside the collector had a small effect on the speed of the air inside the chimney and tends to change slightly, hence, can neglect influence of wind speed on the performance of the system. Also the experimental results indicate that such type of system can trap a suf?cient amount of solar radiation, which elevates the air temperature to a suf?cient value able to generate enough air ?ow to operate a wind turbine to produce electricity; this means the solar chimney system for electricity production can work in the north-western part of Libya in the summer time at least.

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.

Sign in / Sign up

Export Citation Format

Share Document