System development and studies on utilization of concentrated solar beam radiation for polymer processing

Abstract

Various solar energy technologies are being developed to harness the available

environmentally friendly and sustainable solar radiation. New ways of utilizing this

"free" power for different energy consuming processes continue to be created. In

this thesis, a multi-stage solar energy concentrating system has been developed and

its feasibility as a radiation source for polymer processing has been explored. The

solar energy concentrator (SEC) facility comprises a modified Cassegrainian

configuration combined with auxiliary imaging and non-imaging optics, serving as

an alternative energy source for polymer joining, ageing and adhesive curing.

Modeling and improvement of various aspects of the operation and performance of the SEC facility have been implemented. Optical ray tracing models of the Cassegrainian concentrator with various conventional imaging components and nonimaging

concentrators have been created to optimize the optical layout and system efficiency. On their basis, combined 3D ray tracing computer models integrated with

the mechanical components have been developed to simulate the entire SEC facility and predict the image size, location and orientation. Additionally, the energy transfer, radiation absorption and heat generation and transfer in the irradiated polymer have been modeled in order to study the radiation-polymer interaction.

One novel contribution of this research is the enhancement of the image forming concentrator with non-imaging cone-like concentrators (conical and compound

parabolic concentrator (CPC)), utilizing their inherent disadvantage of excessive

length. Compared to the refractive type means of transmitting concentrated solar

radiation, the truncated cone and CPC concentrators have been found more efficient

enhancing further the concentration and widening the utilized spectral range.

The experimental studies have demonstrated that transparent and colored, similar and dissimilar polymers can be successfully joined using the SEC facility.

The especially developed through-transmission technique removes the need to use a special absorbing medium of the radiant energy required by current advanced welding techniques. The tensile strengths of the joints achieved are comparable to those achieved for similar polymers with other advanced plastic joining methods.

The results from the polymer ageing experiments have shown that ultraaccelerated

exposure to concentrated sunlight can be performed with the SEC facility without introducing spurious failure mechanisms. Based on the preliminary investigation on adhesive curing utilizing concentrated solar radiation, it has been concluded that with carefully chosen light-curing adhesives solar radiation can be a useful radiation source for adhesive curing.