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M. Natarajan

Bio: M. Natarajan is an academic researcher from VIT University. The author has contributed to research in topics: Parabolic trough & Heat transfer. The author has an hindex of 5, co-authored 20 publications receiving 41 citations. Previous affiliations of M. Natarajan include M. Kumarasamy College of Engineering.

Papers
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01 Jan 2014
TL;DR: In this paper, numerical analysis using CFD is performed by using inserts of different cross-section inside the fluid flow path of an absorber tube to study the flow characteristics, and the results of numerical analysis is validated with the experiments carried out with the parabolic trough collector.
Abstract: Absorber tube performance enhancement by using passive techniques is one of the major topics of research in the field of solar thermal power engineering. Earlier studies on ducts revealed that passive augmentation techniques have shown considerable enhancement in heat transfer. Experiments were conducted earlier on Parabolic Trough Collector (PTC) with plain absorber tube without inserts for different flow rate conditions. It was observed that fluid flow rate with 85 kg/hr has shown higher temperature difference for solar flux condition of 850 W/m 2 . In the present study, numerical analysis using CFD is performed by using inserts of different cross-section inside the fluid flow path of an absorber tube to study the flow characteristics. The fluid flow and heat transfer phenomena through a 3-dimensional absorber tube with varying heat source are obtained by solving the fundamental governing equations namely: conservation of mass, momentum and energy. Turbulence is modeled using SST k-ω model of closure. The heat transfer and pressure drop is calculated from the studies conducted for a mass flow rate of 85 kg/hr using the ANSYS CFX 12.1 software. The result of the numerical analysis is validated with the experiments carried out with the parabolic trough collector. The numerical study is carried out with triangle, inverted triangle and semi-circular inserts and compared with that of plain absorber tube. It has been found that triangle insertion gives optimized results with respect to uniform heat transfer which reduces the thermal fatigue even the pressure drop is relatively high compared to the plain absorber tube without insertion.

9 citations

Journal ArticleDOI
TL;DR: In this paper, a novel gravity-based passive solar tracking mechanism is proposed to minimize the tracking load and error by controlling in dripping rate or filling rate of liquid in the gravity system.

9 citations

Journal ArticleDOI
TL;DR: In this article, a case study was carried out on a dairy plant to explore the possibility and extent of energy savings using heat pumps resulting in energy cost reduction of 46% in dairy plant.

8 citations

Journal ArticleDOI
TL;DR: In this article, the role of collector orientation on solar geometry has been studied to increase the collection of solar radiation, and the focused surface orientations are (i) horizontal (ii) tilted (iii) zenith angle tracking (iv) azimuth angle tracking and (v) dual axis tracking).
Abstract: In perfect tracking condition, the angle between normal to solar collector’s surface and sunbeam, known as incident angle is zero to gain maximum energy collection and efficiency. The role of collector orientation on solar geometry has been studied to increase the collection of solar radiation. In current work, the focused surface orientations are (i) horizontal (ii) tilted (iii) zenith angle tracking (iv) azimuth angle tracking and (v) dual axis tracking. Sun earth relations (solar geometry) have been solved for a day, seasons and year. Azimuth angle tracking has been suggested over a zenith angle rotation for single axis tracking developers. The zenith angle rotation is favoring only in winter season. In perfect tracking, the tilt angle should be equal to zenith angle and surface azimuth should be equal to solar azimuth angle.

7 citations

Proceedings ArticleDOI
10 Apr 2013
TL;DR: In this paper, numerical analyses have been conducted for the flow of fluid in the absorber tube of a cylindrical parabolic trough collector through CFD technique, where the authors have shown that the efficiency of the tube can be improved by increasing the overall surface area, which increases the heat transfer to the working fluid.
Abstract: In this work, numerical analyses have been conducted for the flow of fluid in the absorber tube of a cylindrical parabolic trough collector through CFD technique. The efficiency of the absorber tube can be improved by increasing the overall surface area, which increases the heat transfer to the working fluid. Analyses of the same have been done to see to what degree the insertions cause an improvement in heat transfer and as a result in increasing the outlet temperature of the working fluid. This has been carried out numerically by commercial CFD code Ansys CFX 12.0. The analysis has been carried out to study the effect of heat transfer in absorber tubes with and without insertions. The study also takes care in distributing different heat flux along the walls of the absorber tubes. The numerical analysis of the absorber tube without any insertions (plain tube) is validated with the experiments carried out on the absorber tube of a solar parabolic trough collector. After validating the numerical analysis, it is extended to study the effect of insertion in the performance of the absorber tube. The working fluid in all these studies is taken as water with different mass flow rates of 33 kg/hr, 63 kg/hr and 85 kg/hr. The temperature at the exit, pressure drop across the absorber tube, wall temperature and velocity along the mid-plane are plotted.

6 citations


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09 Jul 2018
TL;DR: A review of the state of the art and the current research activities of high temperature heat pumps with heat sink temperatures in the range of 90 to 160°C can be found in this paper.
Abstract: Abstract This study reviews the current state of the art and the current research activities of high temperature heat pumps (HTHPs) with heat sink temperatures in the range of 90 to 160 °C. The focus is on the analysis of the heat pump cycles and the suitable refrigerants. More than 20 HTHPs from 13 manufacturers have been identified on the market that are able to provide heat sink temperatures of at least 90 °C. Large application potentials have been recognized particularly in the food, paper, metal and chemical industries. The heating capacities range from about 20 kW to 20 MW. Most cycles are single-stage and differ primarily in the refrigerant (e.g. R245fa, R717, R744, R134a or R1234ze(E)) and compressor type used. The COPs range from 2.4 to 5.8 at a temperature lift of 95 to 40 K. Several research projects push the limits of the achievable COPs and heat sink temperatures to higher levels. COPs of about 5.7 to 6.5 (at 30 K lift) and 2.2 and 2.8 (70 K) are achieved at a sink temperature of 120 °C. The refrigerants investigated are mainly R1336mzz(Z), R718, R245fa, R1234ze(Z), R600, and R601. R1336mzz(Z) enables to achieve exceptionally high heat sink temperatures of up to 160 °C.

246 citations

Journal ArticleDOI
TL;DR: In this paper, a review of current and past studies to assess the optical and thermal performances of parabolic trough solar collectors, modeling approaches and the potential improvements proposed on behalf of the parabolic-trough solar collector design is presented.

206 citations

Journal ArticleDOI
TL;DR: In this paper, a lab-scale PV-assisted solar drying system equipped with a sun tracking unit was designed and fabricated to study the drying behavior of tomato slices during the drying process.

67 citations

Journal ArticleDOI
TL;DR: In this article, a 2D:3D numerical optical, thermal and electric coupling approach for a hybrid compound parabolic concentrator photovoltaic/thermal (CPC-PV/T) collector using a nanofluid as a spectral beam filter is introduced.

54 citations