Abstract
A new experimental model is proposed and tested to enhance the ability of receivers of solar thermal dish collectors in absorbing solar energy. An innovative model consisting of a dual layer, staggered arrangement, and multiscale diameter tubes is established. The enhancement augments the capability of the solar receiver of the collector to transform solar energy to thermal energy within the heat transfer fluid. The new design depends on the exploitation of the dead regions of the solar receiver, that is, surfaces with weak solar energy absorption which include the space between the pipes and the terminal sides of the pipes. The surface areas of the circular pipes in these regions are almost parallel to the solar energy radiation, which leads to a reduction in the ability of the tube to absorb solar energy. The design was validated through five receiver ([Formula: see text]) models for solar thermal dish collectors, in addition to the model base (which has single layer). Each model consists of a two-layer staggered arrangement and tubes with four different staggered diameter ratios [Formula: see text] between the two layers. Each of them has an octagonal shape and consists of three serial paths of copper tubes; each path consists of a bank of parallel tubes. The results show a noteworthy increase in the ability of the receiver to absorb solar energy and greater with model ([Formula: see text]) which [Formula: see text]equal (0.269) than for a plain tube collector. The enhancement leads to an increase in the thermal efficiency [Formula: see text]and exergetic performance [Formula: see text], that equal (78.8%) and (19.8%) respectively at (0.07 kg/s). Furthermore, the pressure difference, and efficiency evaluation criterion was estimated to evaluate dish collector receivers.
Highlights
Solar energy is a potential energy source in view of substantial issues of the energy field such as global warming and fossil fuel depletion.Sunshine is the most abundant source of energy on Earth
Because the thermal losses of the absorber are proportional to its surface, an innovative design is proposed in this study, which involves the exploitation of the whole surface area of the solar receiver, which is exposed to direct solar radiation by placing pipes in front of areas with weak solar absorption on the terminal sides of the pipes that are almost parallel to the direction of the incident solar radiation
The maximum DTðCÞ measured for model Dcr5 (7.4–4.1C) at m_HTF 1⁄4 0.07–0.2 kg/s represents an increase of $54.2%–28.1% compared with model Dcr1
Summary
Solar energy is a potential energy source in view of substantial issues of the energy field such as global warming and fossil fuel depletion.Sunshine is the most abundant source of energy on Earth. Azzouzi et al (2017) experimentally and analytically studied the influence of the receiver inclination angle, water flow rate within the receiver, solar concentration ratio, and report/ ratio between the cavity depth and the aperture diameter L/D on the total heat loss and thermal efficiency of a downward-facing cavity receiver. The experimental results were utilized to verify a numerical model that was established using the Engineering Equation Solver based on which three working fluids (water, thermal oil, and air) were evaluated under different operating conditions.
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