Measurement of longwave radiative properties of energy-saving greenhouse screens

Light intensity, temperature, and humidity are key factors affecting photosynthesis, respiration, and transpiration. Among these factors, temperature is a crucial parameter to establish an optimal greenhouse climate. Temperature can be controlled by using an appropriate climate screen, which has a considerable impact on crop quantity and quality. The precise measurements of longwave radiative properties of screens are vital to the selection of the most suitable screen for greenhouses so that the desired temperature and a favorable environment can be provided to plants during nighttime. The energy-saving capability of screens can also be calculated by using these properties as inputs in a physical model. Two approaches have been reported so far in the literature for the measurement of these properties, i.e., spectrophotometry and wideband radiometry. In this study, we proposed some modified radiation balance methods for determining the total hemispherical longwave radiative properties of different screens by using wide-band radiometers. The proposed method is applicable to materials having zero porosity, partial opacity, and asymmetric screens with 100% solidity. These materials were not studied previously under natural conditions. The existing and proposed methods were applied and compared, and it was found that the radiometric values obtained from the developed methodology were similar to those previously reported in the literature, whereas the existing method gave unstable results with zero reflectance.

[1]  A. Rasheed,et al.  Development of a Building Energy Simulation Model for Control of Multi-Span Greenhouse Microclimate , 2020, Agronomy.

[2]  A. Rasheed,et al.  Determination of Thermal Radiation Emissivity and Absorptivity of Thermal Screens for Greenhouse , 2019, Protected horticulture and Plant Factory.

[3]  A. Rasheed,et al.  Evaluation of Overall Heat Transfer Coefficient of Different Greenhouse Thermal Screens Using Building Energy Simulation , 2018, Protected horticulture and Plant Factory.

[4]  Hyun Woo Lee,et al.  Development and Optimization of a Building Energy Simulation Model to Study the Effect of Greenhouse Design Parameters , 2018, Energies.

[5]  I. Al-helal,et al.  Estimating the Thermal Radiative Properties of Shading Nets Under Natural Outdoor Conditions , 2016 .

[6]  Robert N. Trigiano,et al.  Plant propagation concepts and laboratory exercises , 2016 .

[7]  I. Al-helal,et al.  On the Emissivity and Absorptivity of Plastic Shading Nets under Natural Conditions , 2015 .

[8]  Pedro Ponce,et al.  Greenhouse Design and Control , 2014 .

[9]  K. Sumathy,et al.  Thermal modeling aspects of solar greenhouse microclimate control: A review on heating technologies , 2013 .

[10]  Geoffrey B. Smith,et al.  Polymeric mesh for durable infra-red transparent convection shields: Applications in cool roofs and sky cooling , 2013 .

[11]  I. Al-helal,et al.  A method for determining the long-wave radiative properties of a plastic shading net under natural conditions , 2012 .

[12]  V. V. N. Kishore,et al.  Renewable Energy Engineering and Technology: Principles and practice , 2009 .

[13]  Giuliano Vox,et al.  Effects of the radiometric properties of innovative biodegradable mulching materials on snapdragon cultivation , 2007 .

[14]  S. Castellano,et al.  The Influence of Construction Parameters on Radiometric Performances of Agricultural Nets , 2006 .

[15]  Demetres Briassoulis,et al.  Review Paper (SE—Structures and Environment): Radiometric and Thermal Properties of, and Testing Methods for, Greenhouse Covering Materials , 2000 .

[16]  Shabtai Cohen,et al.  Measuring and predicting Radiometric Properties of Reflective Shade Nets and Thermal Screens , 1999 .

[17]  J. Deltour,et al.  RADIOMETRIC AND THERMAL PROPERTIES OF THE NEW PLASTIC FILMS FOR GREENHOUSE COVERING. , 1989 .

[18]  A. Nisen,et al.  Radiation transfer through covering materials, solar and thermal screens of greenhouses , 1985 .

[19]  B. J. Bailey,et al.  The reduction of thermal radiation in glasshouses by thermal screens , 1981 .

[20]  J. Meijer,et al.  Reduction of Heat Losses from Greenhouses by Means of Internal Blinds with Low Thermal Emissivity , 1980 .

[21]  M. Kindruk,et al.  On a method for determining the , 1973 .

[22]  A. Rasheed,et al.  Measurement of Convective Heat Transfer Coefficients of Horizontal Thermal Screens Under Natural Conditions , 2020, Protected horticulture and Plant Factory.

[23]  Silke Hemming,et al.  Energy saving screen materials : measurement method of radiation exchange, air permeability and humidity transport and a calculation method for energy saving , 2017 .

[24]  M. Möller,et al.  MEASURING RADIOMETRIC PROPERTIES OF SCREENS USED AS CROP COVERS , 2014 .

[25]  Silke Hemming,et al.  RADIOMETRIC PROPERTIES OF AGRICULTURAL PERMEABLE COVERINGS , 2010 .

[26]  Byoung Ryong Jeong,et al.  Analysis of the Insulation Effectiveness of the Thermal Insulator by the Installation Methods , 2009 .

[27]  A. Shukla,et al.  Experimental study of effect of an inner thermal curtain in evaporative cooling system of a cascade greenhouse , 2008 .

[28]  Chiachung Chen,et al.  A Simple Model to Study the Effect of Temperature on the Greenhouse with Shading Nets , 2008 .

[29]  Gernot Renger,et al.  Primary processes of photosynthesis : principles and apparatus , 2008 .

[30]  D. H. Willits,et al.  INTERMITTENT APPLICATION OF WATER TO AN EXTERNALLYMOUNTED, GREENHOUSE SHADE CLOTH TO MODIFY COOLING PERFORMANCE , 2000 .

[31]  H. F. Zornig,et al.  Transmission of Solar and Long-Wavelength Energy by Materials Used as Covers for Solar Collectors and Greenhouses , 1979 .

[32]  David R. Mears,et al.  Reducing Heat Losses in Polyethylene Covered Greenhouses , 1976 .