Executive Summary : | In case of concentrated solar thermal power (CSP) technologies such as linear Fresnel reflectors (LFR), Parabolic Trough Collectors (PTC) and Solar Towers, determination of heat flux distribution on receiver tubes is highly difficult because of prevailing high flux at the receiver surface which precludes the installation of heat flux sensors. The inaccurate knowledge about heat flux distribution on receiver tube leads to inefficient design (high cost) of the solar receiver. Moreover, the existing design of receiver tubes do not account for induced thermal stresses due to non-uniform temperature along the receiver length. This causes high risk for the safe operation of solar power plants. Therefore, in this proposal we aim to design efficient and safe receiver tubes by solving inverse thermo-elastic problem. It involves simultaneous measurement of circumferential temperature distribution and mechanical displacements at the support end of receiver tubes followed by solution of formulated inverse thermo-elastic problem. For the temperature and mechanical displacement measurement, we propose to develop an indoor solar simulator facility with a test rig consisting of PTC and receiver tube embedded with thermocouples and displacement measurement sensors. An in-house numerical code in Python will be developed for the solution of thermo-elastic phenomena in cylindrical system subjected to non-uniform temperature distribution and induced mechanical displacements. Also, an in-house optimization code will be developed for the solution of inverse problem. These two codes together with experimentally measured data will then be used for recovering heat flux distribution and induced thermal stresses on the receiver tube. Different optimization codes based on both deterministic and stochastic search methods will also be developed to ensure stability and convergence of inverse problem. The successful solution of inverse problem would result to accurate knowledge of heat flux distribution on the receiver surface and also induced thermal stresses. With this knowledge, further analysis will be carried out through which a novel design for the receiver tube will be developed for its improved efficiency and also for overall safety of solar thermal power plant. |