The transmission of diffuse light by a sloping roof

Bowman, G.E.

doi:10.1016/0021-8634(70)90081-8

Cited by 24 publications

(4 citation statements)

References 5 publications

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“…The solar position and outside weather conditions also contribute to the τ gh . A variety of studies on the τ gh have considered the incidence angle of solar radiation (Bowman, 1970), weather conditions (Leonidopoulos, 2000;Cabrera et al, 2009), greenhouse orientation (Papadakis et al, 1998;Li et al, 2000), structural members (Critten, 1987), and dust and dirt on the covering (Geoola et al, 1998). Because the results on τ gh vary from 25% to 59%, according to experimental conditions, applying a specific τ gh for the energy input equation was difficult.…”

Section: Al 2009mentioning

confidence: 99%

“…The incidence angle factor for the solar radiation transmissivity was determined based on Bowman (1970). The solar radiation transmissivity was between 0.92 and 1.0 for incidence angles of less than 60°, whereas solar radiation was reduced exponentially as incidence angle increased above 60°.…”

Section: Determination Of Coefficients In the Ste Model For The Test mentioning

confidence: 99%

“…The arrangement of the pots is 6 5b. Based on the solar radiation transmissivity changes (Bowman, 1970), the incidence angle factors were determined as shown in Fig. 5c and 5d for the wall and the roof, respectively.…”

Section: Modified Projected Leaf Area Index (Mplai)mentioning

confidence: 99%

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Surplus thermal energy model of greenhouses and coefficient analysis for effective utilization

Yang

Son

Lee

et al. 2016

Span. j. agric. res.

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This study concentrates on the utilization of surplus thermal energy (STE) in greenhouses. Even in the cold season, the thermal energy input from solar radiation easily exceeds the required amount for heating on a clear day in the temperate or subtropical regions. This excessive solar energy is regarded as STE. There are several studies related to the STE energy (Pavlou, 1991; Suh et RESEARCH ARTICLE OPEN ACCESS AbstractIf a greenhouse in the temperate and subtropical regions is maintained in a closed condition, the indoor temperature commonly exceeds that required for optimal plant growth, even in the cold season. This study considered this excess energy as surplus thermal energy (STE), which can be recovered, stored and used when heating is necessary. To use the STE economically and effectively, the amount of STE must be estimated before designing a utilization system. Therefore, this study proposed an STE model using energy balance equations for the three steps of the STE generation process. The coefficients in the model were determined by the results of previous research and experiments using the test greenhouse. The proposed STE model produced monthly errors of 17.9%, 10.4% and 7.4% for December, January and February, respectively. Furthermore, the effects of the coefficients on the model accuracy were revealed by the estimation error assessment and linear regression analysis through fixing dynamic coefficients. A sensitivity analysis of the model coefficients indicated that the coefficients have to be determined carefully. This study also provides effective ways to increase the amount of STE.Additional key words: energy balance; energy conservation; environmental control; heat pump; heat storage Abbreviations used: FCU (fan coil unit); HST (high temperature heat storage tank); LST (low temperature heat storage tank); mPLAI (modified PLAI, ratio of total projected leaf area to the floor area); PLAI (projected leaf area index, projected area of horizontal leaves per unit of horizontal land below); SHEF (sensible heat emission factor); STE (surplus thermal energy) Citation: Yang, S. H.; Son, J. E.; Lee, S. D.; Cho, S. I.; Ashtiani-Araghi, A.; Rhee, J. Y. (2016). Surplus thermal energy model of greenhouses and coefficient analysis for effective utilization.

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Section: Al 2009mentioning

confidence: 99%

Section: Determination Of Coefficients In the Ste Model For The Test mentioning

confidence: 99%

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Surplus thermal energy model of greenhouses and coefficient analysis for effective utilization

Yang

Son

Lee

et al. 2016

Span. j. agric. res.

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“…In contrast, with the calculation method, the irradiance of solar radiation during the requested period at any point in a greenhouse can be computed using the irradiance of outside global solar radiation. Many studies have been conducted using the calculation method e.g., Nisen, 1962;Manbeck and Aldrich, 1967;Bowman, 1970;Takakura et al, 1971;Kozai and Sugi, 1972;Critten, 1983;Kurata, 1990;Soriano et al, 2004;Cabrera et al, 2009;Cossu et al, 2017 . However, most research calculated the irradiance of solar radiation in greenhouses with a simple structure ignoring sunshine obstacles not in contact with film surface.…”

Section: Introductionmentioning

confidence: 99%

Calculation of the irradiance of solar radiation in a greenhouse with a complex structure using a diagram for sky view factor

Matsuda

Yoshikoshi

Suzuki

et al. 2020

J. Agric. Meteorol.

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The irradiance of solar radiation in a greenhouse with a complex structure was calculated using a diagram for sky view factor DSVF and compared with observed values. Structural materials such as side pillars and rafters and non-structural materials such as lock channels, door frames, and ventilation fans were treated as sunshine obstacles, including lower rafters and equal leg angles in the inner spaces of the greenhouse. Radiation directions simulated using a DSVF were used for calculating the irradiance of diffuse solar radiation. With respect to the irradiance of total solar radiation on a sunny day, the calculated values were found to be higher than the observed values early in the morning. However, the overall fluctuation due to diurnal change of the solar elevation and in the sharp drops due to the sunshine obstacles were reproduced. Furthermore, the diurnal changes of the irradiance of non-direct solar radiation on a sunny day and the irradiance of total and non-direct solar radiations on a cloudy day could also be reproduced. The relative error of the calculated irradiance of daytime from 04 : 00 to 20 : 00 total and non-direct solar radiations to the measured value was 4.3 for the total radiation on the sunny day, 5.5 for the non-direct radiation on the sunny day, 1.1 for the total radiation on the cloudy day, and 0.3 for the non-direct radiation on the cloudy day. The results of this study indicated that the DSVF can be useful for calculating diffuse solar radiation.

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Energy Efficient Growing Structures for Controlled Environment Agriculture

White¹

1979

Horticultural Reviews

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The transmission of diffuse light by a sloping roof

Cited by 24 publications

References 5 publications

Surplus thermal energy model of greenhouses and coefficient analysis for effective utilization

Surplus thermal energy model of greenhouses and coefficient analysis for effective utilization

Calculation of the irradiance of solar radiation in a greenhouse with a complex structure using a diagram for sky view factor

Energy Efficient Growing Structures for Controlled Environment Agriculture

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