In parabolic trough collector, evacuated or non-evacuated glass tubes are more valuable for medium and high-temperature applications to reduce the heat losses from the absorber tube. Use of such glass tubes is not convenient under lower temperature applications because of lower surface temperature and high initial cost. In this work, an effort has been made to improve the performance of the absorber tube by reducing the heat losses without using a glass cover tube. A new technique of cut tube absorber was designed, developed and tested experimentally in the conditioned room by optimizing area with 45% cut on the upper portion of the tube, which does not receive concentrated sunrays and further covered with flat plate. Also, the presence of insulation and coating over cut tube absorber was studied. Water and sigma therm-K was used as a heat transfer medium in order to examine the heat losses for the working fluid having a temperature range below and above 100°C. Experimental results reveal that reduction in overall surface area of the tube and coating leads to a decrease in thermal heat losses by 16.13% in water and 10.13% in sigma therm-K. Increasing the insulation thickness would reduce heat losses more by 7.33% in water and 33.43% in sigma therm-K.
 
Copyright © 2007 by Mohamed A. Sharaf Eldean Ayoub
All rights reserved. 
No part of this work may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the publisher (Mohamed A. Sharaf Eldean Ayoub). For permission requests, write to the publisher, addressed “Attention: Permissions Coordinator,” at the address below.
 
REDS Software Library
https://www.redslibrary.com
Kuala Lumpur Malaysia
mohamedsheraf@redslibrary.com
00601139795943
All Rights Reserved
___________________