An Improved Technique for Computing the Top Heat Loss Factor of a Flat-Plate Collector With a Single Glazing

1988 ◽  
Vol 110 (4) ◽  
pp. 262-267 ◽  
Author(s):  
S. C. Mullick ◽  
S. K. Samdarshi
Keyword(s):  
Flat Plate ◽  
Heat Loss ◽  
Loss Factor ◽  
Empirical Relation ◽  
Iterative Solution ◽  
Maximum Error ◽  
Analytical Form ◽  
Plate Temperature ◽  
Glass Cover ◽  
Semi Empirical

A different approach to evaluate the top heat loss factor of a flat plate solar collector with a single glass cover is proposed. The equation for the heat loss factor in the analytical form is employed instead of the semi-empirical form hitherto employed for solar collectors. The glass cover temperature is, however, estimated by an empirical relation. (This relation replaces the empirical relation for the factor f of the earlier work). Values of the top heat loss factor calculated by this simple technique are within 3 percent (maximum error) of those obtained by iterative solution of the heat balance equations. There is an improvement in accuracy by a factor greater than five over the current semi-empirical equations. The range of variables covered is 50° C to 150° C in absorber plate temperature, 0.1 to 0.95 in absorber coating emittance, and 5 W/m2C to 45 W/m2C in wind heat-transfer coefficient. The effect of variation in air properties with temperature has been taken into account.

Generalized Analytical Equation for the Top Heat Loss Factor of a Flat-Plate Solar Collector With N Glass Covers

1994 ◽  
Vol 116 (1) ◽  
pp. 43-46 ◽  
Author(s):  
S. K. Samdarshi ◽  
S. C. Mullick
Keyword(s):  
Flat Plate ◽  
Heat Loss ◽  
Loss Factor ◽  
Analytical Equation ◽  
Empirical Equations ◽  
Additional Advantage ◽  
Computational Errors ◽  
Flat Plate Solar Collector ◽  
Flat Plate Collector ◽  
Semi Empirical

A generalized analytical equation for the top heat loss factor of a flat-plate collector with one or more glass covers has been developed. The maximum computational errors resulting from the use of the analytical equation with several simplifications are ± 5 percent compared to numerical solution of the set of heat balance equations. The analytical equation is considerably more accurate than the available semi-empirical equations over the entire range of variables covered. An additional advantage of the proposed technique over the semi-empirical equations is that results can be obtained for different values of sky temperature, using any given correlation for convective heat transfer in the air gap spacings, and for any given values of fluid (air in the present case) properties.

Analytical Equation for the Top Heat Loss Factor of a Flat-Plate Collector With Double Glazing

1991 ◽  
Vol 113 (2) ◽  
pp. 117-122 ◽  
Author(s):  
S. K. Samdarshi ◽  
S. C. Mullick
Keyword(s):  
Flat Plate ◽  
Heat Loss ◽  
Loss Factor ◽  
Analytical Equation ◽  
Empirical Equations ◽  
Transfer Coefficients ◽  
Computational Errors ◽  
The Individual ◽  
Flat Plate Collector ◽  
Semi Empirical

An analytical equation for the top heat loss factor of a flat-plate collector with double glazing has been developed. The maximum computational errors resulting from the use of this equation are plus or minus three percent compared to numerical solution of the heat balance equations. The equation is considerably more accurate than the currently used semi-empirical equations over the entire range of variables covered. It is found that the computational errors resulting from simplification of the proposed equation by approximation of the individual heat-transfer coefficients are much lower than the errors resulting from the use of semi-empirical equations.

Glass Cover Temperature and Upward Heat Losses of a Single Glazed Collector With Nearly Vertical Configuration

2010 ◽  
Author(s):  
Suresh Kumar ◽  
Subhash C. Mullick
Keyword(s):  
Numerical Solution ◽  
Flat Plate ◽  
Heat Balance ◽  
Empirical Relation ◽  
Heat Losses ◽  
Operating Conditions ◽  
Balance Equations ◽  
Maximum Absolute Error ◽  
Glass Cover ◽  
Flat Plate Collector

Estimation of upward heat losses is required for design or thermal performance evaluation of a flat plate collector. Collectors with vertical configuration are used at high latitudes and are integrated with building walls. Values of glass cover temperature are required for calculation of upward heat losses under different operating conditions. Glass cover temperature can be determined from numerical solution of heat balance equations. In the present work an empirical relation for glass cover temperature of a single glazed flat plate collector for angle of tilt 60 to 90 degree is proposed. Values of glass cover temperature obtained from this empirical relation have been used for computation of top heat loss coefficient of flat plate collector. Analytical equation has been employed for estimation of Ut. The range of variables covered in the present analysis is 20 °C to 150 °C for absorber plate temperature, 0.1 to 0.95 for absorber coating emittance, 20 mm to 50 mm for air gap spacing, 60 deg to 90 deg for collector tilt, 5 W/m2K to 30 W/m2K for wind heat transfer coefficient and −10 °C to + 40 °C for ambient temperature. The maximum absolute error in values of Ut is within two percent in comparison to values obtained by numerical solution of heat balance equations over the entire range of variables covered in the present work.

scholarly journals Study of Fabricated Solar Dryer of Tomato Slices under Jordan Climate Condition

2017 ◽  
Vol 6 (2) ◽  
pp. 93
Author(s):  
Abdullah Nasrallh Olimat
Keyword(s):  
Ambient Temperature ◽  
Flat Plate ◽  
Heat Loss ◽  
Moisture Diffusivity ◽  
Temporal Variations ◽  
Solar Irradiation ◽  
Climate Condition ◽  
Absorber Plate ◽  
Plate Temperature ◽  
Solar Dryer

The objective of the current study was to investigate experimentally, the performance of a fabricated solar dryer under Jordan climate condition during the summer of 2013. The temporal variations of temperature difference between absorber plate and ambient temperature were obtained in the results and its influence on the performance of solat flat plate collector was examined. The effect of absorber plate temperature, ambient temperature and wind heat transfer coefficient on the top heat loss coefficient was also investigated. The results showed that the efficiency of the collector ranging between 45 to 66 % which affected significantly by the amount of solar irradiation during the day. Only top heat loss was taken into considerations, since other losses were very small and might be negligible. Also the results confirmed that the performance of collector was maximum when the difference between plate and ambient temperatures was maximum. In addition, this work presented an indirect forced convection solar dryer, which consists of solar heater, fan and drying chamber. Fan was used to force the heated air through chamber to increase the drying rate.  A 500 gram of tomatoe were dried to the final moisture content 28% from 95% (w.b). The experimental moisture ratios of the tomatoes were fitted to four mathematical drying models. Comparisons between these modes are sought using statistical analysis in the results. The fit quality obtained with each model was evaluated. After the comparison with the experimental obtained values, it was concluded that polynomial equation with second order represents the drying characteristics better than the other models by indicating high value of coefficient correlation (R2= 0.999564 ) and low values of other parameters( 𝞌2= 0.000203; RMSE= 0.01011; MBE= 0.000102 ) compare with other models. The effective moisture diffusivity was estimated using Fick's second law and was  m2/s with an average temperature of 306 K.Keywords: Moisture ratio; solar drying; moisture diffusivity;thin layer model; flat plate collectorArticle History: Received January 14th 2017; Received in revised form April 28th 2017; Accepted June 10th 2017; Available onlineHow to Cite This Article: Olimat, A.N. (2017) Study of Fabricated Solar Dryer of Tomato Slices Under Jordan Climate Condition. International Journal of Renewable Energy Develeopment, 6(2), 93-101.https://doi.org/10.14710/ijred.6.2.93-101

An Improved Generalized Model for Predicting Frost Growth on a Cold Flat Plate

2010 ◽  
Author(s):  
Q. C. Guo ◽  
W. Wang ◽  
J. Xiao ◽  
W. P. Lu
Keyword(s):  
Experimental Data ◽  
Flat Plate ◽  
Current Model ◽  
Theoretical Models ◽  
Maximum Error ◽  
Open Loop ◽  
Experimental Conditions ◽  
Wide Range ◽  
Semi Empirical ◽  
Frost Growth

A generalized quasi-steady and one-dimensional model for predicting the frost growth on flat plate was proposed based on the previous theoretical models. To improve the predicting ability of the current model, a modified semi-empirical correlation for calculating initial condition of frost density was presented experimentally. The experiments were conducted in a suction-type open-loop wind tunnel under a series of experimental conditions: air temperature −8°C to 19°C, humidity 42% to 80%, velocity 5m/s and the temperature of cold plate −16°C to −8°C. The numerical results of frost thickness, frost density, frost surface temperature and heat flux rate were compared to the experimental data. The simulation results were found agree with the experimental results in a maximum error of 10%. The presented model was further validated by comparing with the previous published experimental data in a wide range of frosting conditions. It was found that the presented model was a simple but universal one to predict the frost growth on cold flat plate.

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