Greenhouse Solar Thermal Application

Greenhouse Solar Thermal Application

Tribeni Das (Das Energy Consulting Pvt. Ltd., India) and Ganesh C. Bora (North Dakota State University, USA)
Copyright: © 2013 |Pages: 18
DOI: 10.4018/978-1-4666-1996-8.ch017
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Abstract

This chapter includes brief description of different solar thermal applications of greenhouse structure based on the different research work done in this area. It provides the basic knowledge of the use of solar energy to increase the production of different agricultural products using greenhouse system, e.g., crop production and drying of agricultural products. The chapter includes the introduction of greenhouse system, the definition, the concept, and the importance of greenhouse technology. The uses of various solar thermal applications in different greenhouse systems such as flat plate collector in greenhouse fish pond system and application of photovoltaic system in greenhouse drying are covered in this chapter.
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Introduction

Greenhouse structures are used to provide the ideal condition required for the growth of agricultural crops throughout the year. The objective of this chapter is to provide a platform to disseminate the fundamental knowledge of greenhouse structure with various solar thermal applications, which includes:

  • Fundamentals of greenhouse technology

  • Different design of greenhouse structures with different solar thermal applications

  • Basic working principles and energy balance

  • Thermal analysis

The aim of this chapter is to provide an insight in the subject. We have drawn materials from different journals and books related to the subject.

According to EncyclopediaC2000 (Anon, 2000) the greenhouse effect for environment is defined as: “Greenhouse Effect, term for the role the atmosphere plays in insulating and warming the earth’s surface. The atmosphere is largely transparent to incoming solar radiation. When this radiation strikes the earth’s surface, some of it is absorbed, there by warming earth’s surface. The surface of the earth emits some of this energy back out in the form of infrared radiation. As this infrared radiation travels through the atmosphere, much of it is absorbed by atmospheric gases such as carbon-dioxide, methane, nitrous oxide and water vapor. These gases then re-emit infrared radiation, some of which strikes and is absorbed by earth. The absorption of infrared energy by atmosphere and earth, called the greenhouse effect, maintains a temperature range on earth that is hospitable to life. Without the greenhouse effect, the earth would be frozen planet with an average temperature of about –18oC (about 0oF)”. Similarly this phenomenon accomplishes at the micro level, for a house having the transparent walls and roofs (glass, Perspex or polyethylene film), when the solar (short wave length) radiation passes through the transparent walls and roofs it is absorbed by some object inside and then warming up the object. The warm object emits heat in the form infrared (long wave length) radiation, which cannot be re-radiated back outside due to glass cover, resulting in increase in temperature. This house is thus called greenhouse. Today greenhouse is mainly used for the maximized the production of crops mainly during the off season, because inside greenhouse the favorable condition for the optimum growth of the agricultural crops is possible. Greenhouse is used to maintain the favorable condition required for increase the productivity of the crop. The environment such as light, air composition, temperature and nature of the root media has significant effect in the production of agricultural crop (Tiwari, 2003).

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Classification Of Greenhouse Systems

On the basis of working principal applications, greenhouse may be broadly classified in the three categories:

  • 1.

    Greenhouse for crop cultivation,

  • 2.

    Greenhouse for crop drying

  • 3.

    Greenhouse as the solar energy collector

    • The detailed classification on this basis is shown in Figure 1.

Figure 1.

Classification of greenhouse system (Source: Tiwari 2003)

Key Terms in this Chapter

Thermal Analysis: Thermal analysis is a branch in material science where properties of material are studied with the change of temperature.

Solar Thermal Application: Applications where solar thermal energy is used.

Greenhouse Fishpond System: The system where greenhouse structure with a fish pond system inside is used for the cultivation of fish is known as greenhouse fish pond system.

Hybrid Greenhouse Dryer: Greenhouse dryer which include photovoltaic thermal hybrid collectors for the drying of crop is known as hybrid greenhouse dryer. Hybrid PV/T system converts solar radiation into thermal and electrical energy.

Greenhouse Dryer: Greenhouse structure used for drying is called greenhouse dryer. Inside greenhouse dryer crops are dried using the solar thermal energy.

Natural Convection: Natural convection is the type of heat transport or circulation of air which is generated by thermal and density effect not by external source.

Greenhouse: Greenhouse is a building where plants are grown.

Forced Convection: Heat convection caused by external sources such as pump etc is known as forced convection or forced mode.

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