Illumination system with compound parabolic retro-reflector for single LCOS panel projection display

In this paper, a new illumination system with ultra high performance (UHP) lamp is proposed for projection display. Parabolic reflector (PR) and compound parabolic retro-reflector (CPR) were jointly used to collect and collimate the light generated from UHP lamp. A polarization converter system (PCS) was used to increase the light efficiency of the projection display system. A beam transformer between PCS and 2f imaging systems was directly used to make the illumination meet the requirement of projection display system. With the consideration of the loss of reflection, the light efficiency in this projection display system was estimated to be 15.6%.

A Four-Wing Compound Parabolic Concentrator(CPC)Design for Heating and Sanitization of Waste Products

Harnessing the freely available source of energy from the sun offers a number of additional benefits. Not least of these benefits is the fact that solar energy is an environmentally sustainable alternative. A four-wing compound parabolic concentrator (CPC) was designed as a modification of the regular non-imaging CPC concentrator that has a widespread use as solar collector. The design is intended to increase the angle of acceptance as well as concentration of energy from the sun. The conceptual design, mathematical formulation as well as construction and initial trial results have been presented in this paper. Pilot trials of the four-wing concentrator used for sanitizing both liquid and waste products produced satisfactory results. Improvements in terms of design as well as material used for construction and better preservation of heat can be considered further in the future research.

Homogenization Function of Microchannel on Heat Absorber with Compound Parabolic Concentrator

Microchannels offer unique advantages on heat transfer performance. In this paper, microchannels are applied to the compound parabolic concentrator(CPC) system. A multi-physical field coupling model based on Finite Element Method is proposed to investigate the homogenization effect of the microchannel heat absorber on the CPC non-uniform concentration. The energy conversion process from optics to heat is simulated using TracePro software, and the heat transfer processes in the microchannel are computed by Fluent using user defined functions(UDF). It is found that the microchannels behave well on weakening the influence of the nonuniformity solar heat flux on the performance of the CPC. The temperature nonuniformity of the outlet section is less than 10^(-3) in the direction of fluid flow caused by the microchannel, although the maximum surface heat flux inhomogeneity of the microchannel reaches 2.3. The peak value of the heat flux on the surface of the absorber changes from double peak to single peak, and moves to the edge, resulting in more uneven heat flux distribution with the increase of the incident angle within the acceptance semi-angle of the CPC. The result of TracePro clearly shows that when the concentration ratio is less than 5, the heat flux nonuniformity on the surface of the absorber decreases with the increase in concentration ratio. It was interestingly found that the temperature distribution of the heat transfer fluid has weak sensitivity to the changes of truncation ratio. This work provides a way to design a CPC solar collector.

Heat Leakage Numerical Investigation of a Compound Parabolic ConcentratorPulsating Heat Pipe Solar Collector

As a new type of equipment for solar medium temperature utilization, the compound parabolic concentrator-pulsating heat pipe solar collector(CPC-PHPSC) uses pulsating heat pipe(PHP) as an endotherm, which can realize efficient energy conversion. The design of proper concentration ratio of compound parabolic concentrator(CPC) ensures that the incident sunlight can be concentrated on the evaporator section surface of PHP without solar tracking system. The objective of the present work is to study the influence of solar radiation intensity, air speed, material thickness(glass and insulation board) and tilt angle on the thermal performance of the new collector, which is difficult to control in the experiment. The heat leakage process and characteristics of the CPC-PHPSC were numerically studied by establishing a 3D numerical model of the collector unit. The results show that the theoretical collector efficiency of CPC-PHPSC reaches 74.5%, which is consistent with the experimental results. During operation, the heat collection performance is the best when the tilt angle is 45° and the solar radiation intensity is 1000 W/m^(2), while the excessive air speed will increase the convective heat loss. Increasing the thickness of insulation board and glass has little effect on the collector efficiency.

Experimental evaluation of factors affecting performance of concentrating photovoltaic/thermal system integrated with phase‐change materials(PV/T‐CPCM)

The photovoltaic/thermal(PV/T)system is a promising option for countering energy shortages.To improve the performance of PV/T systems,compound parabolic concentrators(CPCs)and phase-change materials(PCMs)were jointly applied to construct a concentrating photovoltaic/thermal system integrated with phase-change materials(PV/T-CPCM).An open-air environment is used to analyze the effects of different parameters and the intermittent operation strategy on the system performance.The results indicate that the short-circuit current and open-circuit voltage are positively correlated with the solar irradiance,but the open-circuit voltage is negatively correlated with the temperature of the PV modules.When the solar irradiance is 500 W⋅m^(−2) and the temperature of the PV modules is 27.5℃,the short-circuit current and open-circuit voltage are 1.0 A and 44.5 V,respectively.Higher solar irradiance results in higher thermal power,whereas the thermal efficiency is under lower solar irradiance(136.2-167.1 W⋅m^(−2) is twice under higher solar irradiance(272.3-455.7 W⋅m^(−2))).In addition,a higher mass flow rate corresponds to a better cooling effect and greater pump energy consumption.When the mass flow rate increases from 0.01 to 0.02 kg⋅s^(-1),the temperature difference between the inlet and outlet decreases by 1.8℃,and the primary energy-saving efficiency decreases by 0.53%.The intermittent operation of a water pump can reduce the energy consumption of the system,and the combination of liquid cooling with PCMs provides better thermal regulation and energy-saving effects under various conditions.