scholarly journals Fast Heating Model for the Aircraft Cabin Air

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3565 ◽  
Author(s):  
Zhi Yang ◽  
Zhengwei Long ◽  
Guangwen Wang
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Temperature Gradient ◽  
Air Temperature ◽  
Environmental Control ◽  
Thermal Environment ◽  
Heating Process ◽  
Fast Heating ◽  
Aircraft Cabin ◽  
Heating Model

Maintaining a suitable cabin air temperature distribution is essential for providing an acceptable thermal environment for passengers and crew. However, cabin air may be very cold for the first flight in winter morning. It could be difficult to heat quickly the cabin air and to maintain an acceptable temperature gradient before boarding with the existing environmental control system. This study developed numerical model for predicting the heating process that coupled airflow and heat transfer in a cabin. The model was validated by using the experimental data obtained from an MD-82 airliner. With the validated numerical model, this investigation proposed to use an electric blanket to heat cabin air quickly and to reduce the air temperature gradient.

Numerical Simulation for Microconvection Around Nano-Particle With Brownian Motion in Liquid

2003 ◽  
Author(s):  
B. X. Wang ◽  
H. Li ◽  
X. F. Peng ◽  
L. X. Yang
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Brownian Motion ◽  
Numerical Model ◽  
Temperature Gradient ◽  
Transfer Process ◽  
Heat Transfer Process ◽  
Nano Particles ◽  
Analytic Method ◽  
Nano Particle

The development of a numerical model for analyzing the effect of the nano-particles’ Brownian motion on the heat transfer is described. By using the Maxwell velocity distribution relations to calculate the most possible velocity of fluid molecules at certain temperature gradient location around the nano-particle, the interaction between fluid molecules and one single nano-particle is analyzed and calculated. Based on this, a syntonic system is proposed and the coupled effect that Brownian motion of nano-particles has on fluid molecules is simulated. This is used to formulate a reasonable analytic method, facilitating laboratory study. The results provide the essential features of the heat transfer process, contributed by micro-convection to be considered.

scholarly journals Evaluating the Effect of Cover Materials on Greenhouse Microclimates and Thermal Performance

Agronomy ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 143
Author(s):  
Hyung-Kweon Kim ◽  
Si-Young Lee ◽  
Jin-Kyung Kwon ◽  
Yong-Hyeon Kim
Keyword(s):  
Heat Transfer ◽  
Energy Savings ◽  
Environmental Control ◽  
Thermal Environment ◽  
Single Layer ◽  
Cold Season ◽  
Maximum Heat ◽  
Air Temperatures ◽  
Maximum Heat Transfer ◽  
Load Leveling

This study compared and analyzed changes in the microclimate and thermal environment inside single-span greenhouses covered with a single layer of plastic film, polycarbonate (PC), and glass. The results of the experiment show that the PC-covered greenhouse was the most favorable for managing the nighttime heating effect during the cold season. However, the glass-covered greenhouse was found to be the most favorable for managing the cooling effect during the hot season. Although the plastic-covered greenhouse was inexpensive and easy to install, the air temperature inside varied significantly, and it was difficult to control its indoor environment. The thermal load leveling values showed that the PC-covered greenhouse had the lowest variation, confirming its superiority in terms of environmental control and energy savings. In terms of the overall heat transfer, heat was generally transferred from the interior to the exterior of the greenhouses. In the plastic-covered greenhouse, however, heat was transferred in the opposite direction at night due to the influence of radiant cooling. The occurrence of the minimum and maximum heat transfer values had a tendency similar to that of the occurrence of the minimum and maximum air temperatures inside the greenhouses.

The influence of solar panel roof on urban thermal environment and cooling energy demand during a heat wave event in 2017

2020 ◽  
Author(s):  
Yongwei Wang ◽  
Fei Chen ◽  
Xiaolong Hao ◽  
Fan Wang
Keyword(s):  
Heat Transfer ◽  
Power Generation ◽  
Energy Consumption ◽  
Air Temperature ◽  
Energy Supply ◽  
Energy Demand ◽  
Thermal Environment ◽  
Clean Energy ◽  
Solar Panel ◽  
Cooling Effect

<p>With the rapid development of social economy, China's energy demand has been growing at an alarming rate. The annual cumulative power generation is about  6.8 trillion kilowatts hour in 2017, and 70% of them is provided by fossil fuel resources, so it is important to promote the use of renewable and clean energy, such as solar power generation technology. The advantages of using solar panel roof in urban areas include reduction of the need of land use in the crowed city and less dependence on fossil fuels. However, there is need to understand impacts of solar roof on local climate, on energy supply during heatwaves, and associated economic benefits in China. This study selected a heatwave event in Jiangsu province, China to simulate the impact of solar panel roof on local thermal environment and energy supply. During that time, the cooling energy consumption reached more than half of the total electricity consumption. A new heat transfer scheme of solar panel roof was introduced into WRF/BEP/BEM model, which include layers (glass protective panel, solar panel, bottom plate) and was divided into two types for heat transfer calculation: bracket and non-bracket. The results showed that the urban average 2-m daytime temperature decreased by 0.3℃ in non-bracket case which is better than that of bracket case, while its cooling effect on nighttime temperature was small. For the bracket case, its cooling effect on daytime and nighttime air temperature were equal (0.2<sup>o</sup>C). Both solar panel roofs can reduce indoor daytime air temperature with the maximum cooling effect around 11:00 local time for non-bracket roof and 14:00 for bracket roof. However, bracket roof increased nighttime indoor air temperature and air-conditioning energy consumption. Solar panel roofs also reduce daytime turbulent kinetic energy and constrain the development of boundary layer. Results also show that with solar photoelectric conversion efficiency being 0.14, the photovoltaic power generation can meet 84.1%, 61.3% and 35.9% of the cooling energy consumption for high-density, low-density residential areas and commercial areas, respectively, during this heatwave event.</p>

scholarly journals Modelling investigation of water droplet evaporative freezing in artificial snowmaking

2019 ◽  
Vol 128 ◽  
pp. 06013
Author(s):  
Georges El Achkar ◽  
Aiqiang Chen ◽  
Rachid Bennacer ◽  
Bin Liu
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Relative Humidity ◽  
Air Temperature ◽  
Water Droplet ◽  
Theoretical Models ◽  
Comsol Multiphysics ◽  
Initial Diameter ◽  
Air Space ◽  
Mass And Heat Transfer

In this paper, a modelling investigation of water droplet evaporative freezing was conducted in order to better understand the snowmaking process and hence to optimise the design of the artificial snowmaking device. To this end, mass and heat transfer theoretical models of a single water droplet cooling in an air space were established and implemented in a numerical model developed using the software COMSOL Multiphysics. The effects of the air temperature, relative humidity and velocity and the water droplet initial diameter and temperature on this process were identified and analysed, and their appropriate ranges for the snowmaking were determined.

Heat Transfer Mechanisms During Short-Pulse Laser Heating of Metals

1993 ◽  
Vol 115 (4) ◽  
pp. 835-841 ◽  
Author(s):  
T. Q. Qiu ◽  
C. L. Tien
Keyword(s):  
Heat Transfer ◽  
Boltzmann Equation ◽  
Laser Heating ◽  
Short Pulse ◽  
Current Model ◽  
Heating Process ◽  
Inelastic Electron ◽  
Fast Heating ◽  
The Boltzmann Equation ◽  
Transfer Mechanisms

This work studies heat transfer mechanisms during ultrafast laser heating of metals from a microscopic point of view. The heating process is composed of three processes: the deposition of radiation energy on electrons, the transport of energy by electrons, and the heating of the material lattice through electron-lattice interactions. The Boltzmann transport equation is used to model the transport of electrons and electron-lattice interactions. The scattering term of the Boltzmann equation is evaluated from quantum mechanical considerations, which shows the different contributions of the elastic and inelastic electron-lattice scattering processes on energy transport. By solving the Boltzmann equation, a hyperbolic two-step radiation heating model is rigorously established. It reveals the hyperbolic nature of energy flux carried by electrons and the nonequilibrium between electrons and the lattice during fast heating processes. Predictions from the current model agree with available experimental data during subpicosecond laser heating.

scholarly journals Simulation of Thermal Transfer Through the Polyamide Intake Manifold

2019 ◽  
Vol 56 (1) ◽  
pp. 190-193
Author(s):  
Corneliu Birtok-Baneasa ◽  
Adina Budiul-Berghian ◽  
Virginia Ana Socalici ◽  
Robert Bucevschi
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Boundary Layer ◽  
Numerical Model ◽  
Air Temperature ◽  
Wall Temperature ◽  
Thermal Boundary Layer ◽  
Intake Manifold ◽  
Thermal Transfer ◽  
Steady Heat

The aim of the present study is to model the steady heat transfer of the engine polyamide intake manifold. Under the condition of a steady flow, the intake manifold wall temperature and the intake air temperature were measured to examine the effect of the thermal boundary layer on the heat transfer. Experimental data is used to generate the numerical model of airflow simulation through the intake manifold.

Heat Transfer Analysis in Environmental Control Using an Underground Air Tunnel

1985 ◽  
Vol 107 (2) ◽  
pp. 141-145 ◽  
Author(s):  
D. Y. Goswami ◽  
A. S. Dhaliwal
Keyword(s):  
Heat Transfer ◽  
Soil Temperature ◽  
Air Temperature ◽  
Environmental Control ◽  
Theoretical Calculations ◽  
Heat Transfer Analysis ◽  
Pipe Length ◽  
Pipe Surface ◽  
Air Flow Velocity ◽  
Good Agreement

This paper presents heat transfer analysis of a passive summer cooling and winter preheating technique, which utilizes the underground temperature at a depth of 6 ft (1.83m) or more. In this study, a computer model solution has been developed for predicting the air temperature at any point, at any time while passing through the underground pipe. The air temperature is a function of the inlet air temperature and humidity, soil temperature, soil properties, the pipe (length, diameter, shape, and material), and the air flow velocity. Experiments were performed to measure air temperature, soil temperature, and pipe surface temperature at different lengths and different intervals of times. The results of the experiments are compared with theoretical calculations, which showed very good agreement. Thus the theoretical model may be used for predicting the performance of such systems in the future.

Technical Note. Influence of Material Used for the Regenerator on the Properties of a Thermoacoustic Heat Pump

2013 ◽  
Vol 38 (4) ◽  
pp. 565-570 ◽  
Author(s):  
Bartłomiej Kruk
Keyword(s):  
Heat Transfer ◽  
Temperature Gradient ◽  
Acoustic Wave ◽  
Heat Pump ◽  
Sound Wave ◽  
Heat Exchangers ◽  
Heat Pumps ◽  
Technical Note ◽  
New Materials ◽  
Modern Technologies

Abstract Research in termoacoustics began with the observation of the heat transfer between gas and solids. Using this interaction the intense sound wave could be applied to create engines and heat pumps. The most important part of thermoacoustic devices is a regenerator, where press of conversion of sound energy into thermal or vice versa takes place. In a heat pump the acoustic wave produces the temperature difference at the two ends of the regenerator. The aim of the paper is to find the influence of the material used for the construction of a regenerator on the properties of a thermoacoustic heat pump. Modern technologies allow us to create new materials with physical properties necessary to increase the temperature gradient on the heat exchangers. The aim of this paper is to create a regenerator which strongly improves the efficiency of the heat pump.

scholarly journals A numerical model and validation of phase change material integrated thermoelectric radiant cooling panel

2019 ◽  
Vol 111 ◽  
pp. 01001
Author(s):  
Hansol Lim ◽  
Hye-Jin Cho ◽  
Seong-Yong Cheon ◽  
Soo-Jin Lee ◽  
Jae-Weon Jeong
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Numerical Model ◽  
Surface Temperature ◽  
Phase Change ◽  
Transfer Coefficient ◽  
Phase Change Material ◽  
Overall Heat Transfer Coefficient ◽  
Radiant Cooling ◽  
Change Material

A phase change material based radiant cooling panel with thermoelectric module (PCM-TERCP) is proposed in this study. It consists of two aluminium panels, and phase change materials (PCMs) sandwiched between the two panels. Thermoelectric modules (TEMs) are attached to one of the aluminium panels, and heat sinks are attached to the top side of TEMs. PCM-TERCP is a thermal energy storage concept equipment, in which TEMs freeze the PCM during the night whose melting temperature is 16○C. Therefore, the radiant cooling panel can maintain a surface temperature of 16◦C without the operation of TEM during the day. Furthermore, it is necessary to design the PCM-TERCP in a way that it can maintain the panel surface temperature during the targeted operating time. Therefore, the numerical model was developed using finite difference method to evaluate the thermal behaviour of PCM-TERCP. Experiments were also conducted to validate the performance of the developed model. Using the developed model, the possible operation time was investigated to determine the overall heat transfer coefficient required between radiant cooling panel and TEM. Consequently, the results showed that a overall heat transfer coefficient of 394 W/m2K is required to maintain the surface temperature between 16○C to 18○C for a 3 hours operation.

scholarly journals Comparison of Building Simulation Methods for Modeling Apartment Balconies

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3955
Author(s):  
Yonghan Ahn ◽  
Hanbyeol Jang ◽  
Junghyon Mun
Keyword(s):  
Heat Transfer ◽  
Air Temperature ◽  
Parameter Analysis ◽  
Interior Space ◽  
Heating And Cooling ◽  
Significant Difference ◽  
Calculation Results ◽  
Infiltration Parameter ◽  
The Difference ◽  
Heating And Cooling Load

The purpose of this study is to compare the load calculation results by a model using the air changes per hour (ACH) method and a model using an airflow network (AFN) and to ascertain what causes the difference between the two models. In the basic case study, the difference in the heat transfer distribution of the model in the interior space was investigated. The most significant difference between the two models is the heat transfer that results from infiltration. Parameter analysis was performed to investigate the relationship between the difference and the environmental variables. The result shows that the greater the difference is between the air temperature inside the balcony and the outdoor air temperature, and the greater the air flows from the balcony to the residential area, and the greater the heating and cooling load difference occurs. The analysis using the actual weather files of five domestic cities in South Korea rather than a virtual case shows that the differences are not so obvious when the wind blows at a constant speed throughout the year, but are dominant when the wind does not blow during the night and is stronger alongside the occurrence of sunlight during the day.

Sign in / Sign up

Export Citation Format

Share Document