Direct Circulation Systems

Direct Circulation System

A schematic diagram of a direct circulation system is shown in Figure 5.9. In this system, a pump is used to circulate potable water from storage to the collectors when there is enough available solar energy to increase its temperature and then return the heated water to the storage tank until it is needed. Because a pump is used to circulate the water, the collectors can be mounted either above or below the storage tank. Direct circulation systems often use a single storage tank equipped with...

Thermal Analysis Of Flatplate Collectors

Tilted Flat Plate Collector

In this section, the thermal analysis of the collectors is presented. The two major types of collectors, flat plate and concentrating, are examined separately. The basic parameter to consider is the collector thermal efficiency. This is defined as the ratio of the useful energy delivered to the energy incident on the collector aperture. The incident solar flux consists of direct and diffuse radiation. While flat-plate collectors can collect both, concentrating collectors can utilize direct...

Suntracking Concentrating Collectors

Sun Collector Convection

Energy delivery temperatures can be increased by decreasing the area from which the heat losses occur. Temperatures far above those attainable by flat-plate collectors can be reached if a large amount of solar radiation is concentrated on a relatively small collection area. This is done by interposing an optical device between the source of radiation and the energy-absorbing surface. Concentrating collectors exhibit certain advantages over the conventional flat-plate type Kalogirou et al.,...

The Multi Stage Flash MSF Process

Multi Stage Flash Solar Desalination

The MSF process is composed of a series of elements, called stages. In each stage, condensing steam is used to pre-heat the seawater feed. By fractionating the overall temperature differential between the warm source and seawater into a large number of stages, the system approaches ideal total latent heat recovery. Operation of this system requires pressure gradients in the plant. The principle of operation is shown in Figure 8.4. Current commercial installations are designed with 10-30 stages...

Concentrating Collectors

Truncated Compound Parabolic Collector

As we have seen in Section 3.2, concentrating collectors work by interposing an optical device between the source of radiation and the energy-absorbing surface. Therefore, for concentrating collectors, both optical and thermal analyses are required. In this book, only two types of concentrating collectors are analyzed compound parabolic and parabolic trough collectors. Initially, the concentration ratio and its theoretical maximum value are defined. The concentration ratio C is defined as the...

Optimum Collector Temperature

Iso 9806 Report

By substituting Eqs. 3.133 and 3.134 into Eq. 3.142 , the rate of entropy generation can be written as S Ur Tr _ T0 _ Q Q _ UrAr Tr _ T0 3.145 By applying Eq. 3.137 in 3.145 and performing various manipulations, The dimensionless term, Sgen UrAr, accounts for the fact that the entropy generation rate scales with the finite size of the system, which is described by By differentiating Eq. 3.146 with respect to 9 and setting it to 0, the optimum collector temperature 9opt for minimum entropy...