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A numerical study is carried out to determine the heat losses caused by natural and forced convection as well as radiation from the parabolic secondary receiver of a Solar Linear Fresnel Reflector system. The geometric configuration considered corresponds to an absorber tube placed in an open aperture. Thermal performance of the receiver with the acceptance angle θ a = 45°, truncation point H/W = 0.6, focal position of the absorber f = 7.9 m and gap between the secondary reflector and absorber tube (G) to the height of the secondary reflector (H) at G/H = 0.14 are considered for the thermal analysis. Thermal losses from the reflector over a wide range of temperature ( 373 K − 773 K ) , diameter ratio ( 0.14 − 0.27 ) and emissivity ( 0.01 − 1 ) are analysed. Realistic conditions including the effects of wind and commerically available absorber diameter and emissivity values are considered to assess the performance of the receiver. Investigation is carried out to determine the heat losses at wind velocities up to 10 m/s. Nusselt number correlations are proposed for determining the heat losses from a solar cavity open aperture with CPC profile. The proposed correlations are functions of the temperature ratio ( T h / T ∞ ) , diameter ratio, emissivity, Grashof number and Reynolds number and they are very useful for predicting the heat losses from the linear receiver of a typical solar LFR system.

Among all passive methods for photovoltaics (PV) cooling, phase change material (PCM) can be highly effective due to high latent heat capacity. However, very low thermal-conductivity of PCM restricts its potential. The proposed work focuses on the enhancement of rate of heat transfer from PV to PCM by using conductivity-enhancing-containers. The proposed approach was experimented outdoor and compared with the reference panel for different seasons at Chennai, India. PV temperature, open circuit voltage, short circuit current, Current-Voltage (I–V) and Power-Voltage (P–V) curves, fill-factors, power outputs, efficiency and daily electricity generation are reported. The results show that the proposed heat sink was able to decrease the maximum PV temperature from 64.4 °C to 46.4 °C for January and 77.1 °C to 53.8 °C for June. It increased the open circuit voltage of PV from 24.3 V to 26.4 V for January and 23.6 V to 26.0 V for June. The fill-factor increased from 0.678 to 0.705 for January. Consequently, the electrical efficiency increased from 9.5% to 10.5% during noon. Daily electricity generation increased from 769 Wh/day to 817 Wh/day during January and 948 Wh/day to 1026 Wh/day during June. Thus, daily electricity generation increased by 6.2% for January and 8.3% for June using proposed approach.

In the present work, structural and optical analysis of 23.08 m2 (Aaperture) solar parabolic trough has been done utilizing different composite materials with an optimized modelling approach. The linear parabolic trough collector is subjected to gravity and wind loads and thereby it undergoes surface deformations. Various trough materials are structurally analysed and a hybrid composite is designed. The RMS values of local slope deviations of trough termed as SD value is calculated using Modified Element Approach to observe the behaviour of trough at various tracking positions varying from 0° to 90° orientations. The cases been discussed are trough-alone (stiff) case and full collector (elastic) case under gravity and wind loading conditions with wind speed of 15 m/s. Trough parameters like fibre orientation of laminae, stacking sequence and direction and size of reinforcement conduits are optimized to minimize SD values. Furthermore, the setup is optically studied and the slope deviations are compared for individual models through intercept factors (γ). The comparative study reveals that the solar parabolic trough collector with its facets made of woven jute/glass fibre-reinforced polyester hybrid composite material yields γmax = 0.957 for avg. SD = 1.34 mrad in stiff case and γmax = 0.955 for avg. SD = 1.349 mrad in elastic case under gravity load, and γmax = 0.866 for avg. SD = 3.78 mrad in stiff case and γmax = 0.863 for avg. SD = 3.81 mrad in elastic case under both wind and gravity loads, resulting to be the best among considered models. Maximum weight reduction of up to 30% in stiff case and up to 4.5% in elastic case has also been observed compared to conventional glass collector for hybrid composite model thus reducing the tracking power and producing a cost effective system.