scholarly journals A Study to Explore the Dew Condensation Potential of Cars

Atmosphere ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 65
Author(s):  
Marc Muselli ◽  
Danilo Carvajal ◽  
Daniel A. Beysens
Keyword(s):  
Visual Observation ◽  
Climatic Conditions ◽  
Atmospheric Water ◽  
Transfer Coefficients ◽  
Thermal Isolation ◽  
Heat Transfer Coefficients ◽  
Observation Scale ◽  
Dew Formation ◽  
Planar Film ◽  
Different Climates

The metal surfaces of a car exhibit favorable properties for the passive condensation of atmospheric water. Under certain nocturnal climatic conditions (high relative humidity, weak windspeed, and total nebulosity), dew is often observed on cars, and it is appropriate to ask the question of using a vehicle as a standard condenser for estimating the dew yield. In order to see whether cars can be used as reference dew condensers, we report a detailed study of radiative cooling and dew formation on cars in the presence of radiating obstacles and for various windspeeds. Measurements of temperature and condensed dew mass on different car parts (rooftop, front and back hoods, windshield, lateral and back windows, inside and outside air) are compared with the same data obtained on a horizontal, thermally isolated planar film. The paper concludes that heat transfer coefficients, evaluated from temperature and dew yield measurements, are found nearly independent of windspeed and tilt angles. Moreover, this work describes the relation between cooling and dew condensation with the presence or not of thermal isolation. This dependence varies with the surface tilt angle according to the angular dependence of the atmosphere radiation. This work also confirms that cars can be used to estimate the dew yields in a given site. A visual observation scale h = Kn, with h the dew yield (mm) and n = 0, 1 2, 3 an index, which depends whether dew forms or not on rooftop, windshield, and lateral windows, is successfully tested with 8 different cars in 5 sites with three different climates, using K = (0.067 ± 0.0036) mm.day−1.

Evaluating the Performance of Single Slope Passive Solar Still for Different Slope of Cover and Water Depths by Thermal Modeling: In Moderate Climatic Condition

Solar Energy ◽  
2006 ◽  
Author(s):  
Anil Kr. Tiwari ◽  
G. N. Tiwari
Keyword(s):  
Heat Transfer ◽  
Thermal Modeling ◽  
Internal Heat ◽  
Ambient Air ◽  
Climatic Conditions ◽  
Transfer Coefficients ◽  
Comparative Performance ◽  
Heat Transfer Coefficients ◽  
Passive Solar ◽  
Water Depths

In this communication, the comparative performance of three passive solar distillation units is studied simultaneously having three different inclinations of condensing covers namely 15°, 30° and 45° of same basin area of 1m2 for varying water depths lower (0.04m), medium (0.08m) and higher (0.12m) respectively. The convective and evaporative heat transfer coefficients are evaluated by regression analysis and further used in thermal modeling to predict the yield. The effect of inclination at different water depths has been studied by conducting outdoor experiments for Delhi climatic conditions in the month of March 2005. The hourly variations of water, vapor, and cover temperatures along with yield insolation, ambient air velocity for three distillation units at different water depths have been measured as observations. A fair agreement has been observed between theoretical and experimental results by using the evaluated internal heat transfer coefficients based on inner glass cover temperature.

Effects of Exterior Sun Shades on Heat Transfer by Solar Radiation

2014 ◽  
Vol 935 ◽  
pp. 61-65 ◽  
Author(s):  
Chih Hong Huang ◽  
Shin Yu Tsai
Keyword(s):  
Heat Transfer ◽  
Solar Radiation ◽  
Building Materials ◽  
Precast Concrete ◽  
Climatic Conditions ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Wall Structures ◽  
Solar Radiation Intensity ◽  
Reduced Scale

Heat transfer in walls, as affected by climatic conditions such as fluctuations in outside air temperature, solar radiation intensity and wind speed as well as wall structures and heat transfer coefficients of materials, becomes a complex and non-steady state. The aim of this paper is to examine the relationship between total whole-day solar radiation and heat absorbed by and released from materials. An reduced scale of experiment was conducted using reduced scale precast concrete slabs and focusing on the effect of heat transfer involving solar radiation, building materials and shading rate. The results show that even though the sun shadings would stem partly the solar radiation into the wall, yet they obstruct in the mean time the release of the heat, which absorbed hours ago. That leads to a temperature raise and uncomfort to the interiors.

scholarly journals EXPERIMENTAL FORCED SOLAR THIN LAYER GINGER DRYING

2016 ◽  
Vol 14 (1) ◽  
pp. 101 ◽  
Author(s):  
Mahesh Kumar
Keyword(s):  
Heat Transfer ◽  
Linear Regression Analysis ◽  
Zingiber Officinale ◽  
Climatic Conditions ◽  
Transfer Coefficients ◽  
Average Value ◽  
Heat Transfer Coefficients ◽  
Collector Efficiency ◽  
C And N ◽  
Evaporative Heat Transfer

In this research paper, the convective and the evaporative heat transfer coefficients of ginger (zingiber officinale) drying in an indirect solar cabinet dryer under the induced forced convection mode is presented. Experiments were conducted during the month of March 2015 under the climatic conditions of Hisar, India (29°5’5”N latitude and 75°45’55”E longitude). The experimental data obtained for solar drying of a constant ginger mass of 150 g has been used to determine constants ‘C’ and ‘n’ in the Nusselt number expression using linear regression analysis; consequently, the convective and the evaporative heat transfer coefficients have been evaluated. The average value of constants ‘C’ and ‘n’ were evaluated as 0.999 and 0.318, respectively. The average values of the convective and the evaporative heat transfer coefficients were found to be 3.95 W/m2 °C and 160.47 W/m2 °C, respectively, for the given mass samples of ginger. The average collector efficiency was observed to be 14.5%. The experimental error in terms of percentage uncertainty was found to be 20.87%.

scholarly journals Analytical thermal modeling of double slope solar still by using inner glass cover temperature

2008 ◽  
Vol 12 (3) ◽  
pp. 139-152 ◽  
Author(s):  
Kumar Shukla ◽  
Ajeet Rai
Keyword(s):  
Internal Heat ◽  
Climatic Conditions ◽  
Solar Still ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Glass Cover ◽  
Solar Distillation ◽  
Indian Climatic ◽  
C And N ◽  
Internal Heat Transfer

In this paper, expressions for water and glass temperatures, hourly yield and instantaneous efficiency for double slope solar distillation systems have been derived analytically. The analysis is based on the basic energy balance for the systems. A thermal model has been developed to predict the performance of the still based on both, the inner and the outer glass temperatures of the solar still. In the present work two sets of values of C and n of internal heat and mass transfer coefficients, obtained from the experimental data under Indian climatic conditions, have been used. It is concluded that (1) there is a significant effect of operating temperature range on the internal heat transfer coefficients and (2) by considering the inner glass cover temperature there is reasonable agreement between the experimental and predicted theoretical results.

Exergy and sensibility analysis of each individual effect in a kraft multiple effect evaporator

TAPPI Journal ◽  
2019 ◽  
Vol 18 (10) ◽  
pp. 607-618
Author(s):  
JÉSSICA MOREIRA ◽  
BRUNO LACERDA DE OLIVEIRA CAMPOS ◽  
ESLY FERREIRA DA COSTA JUNIOR ◽  
ANDRÉA OLIVEIRA SOUZA DA COSTA
Keyword(s):  
Optimization Problem ◽  
Real Data ◽  
Kraft Pulping ◽  
Steam Temperature ◽  
Input Flow ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Multiple Effect ◽  
Sensibility Analysis ◽  
Exergetic Analysis

The multiple effect evaporator (MEE) is an energy intensive step in the kraft pulping process. The exergetic analysis can be useful for locating irreversibilities in the process and pointing out which equipment is less efficient, and it could also be the object of optimization studies. In the present work, each evaporator of a real kraft system has been individually described using mass balance and thermodynamics principles (the first and the second laws). Real data from a kraft MEE were collected from a Brazilian plant and were used for the estimation of heat transfer coefficients in a nonlinear optimization problem, as well as for the validation of the model. An exergetic analysis was made for each effect individually, which resulted in effects 1A and 1B being the least efficient, and therefore having the greatest potential for improvement. A sensibility analysis was also performed, showing that steam temperature and liquor input flow rate are sensible parameters.

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