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One of the unique features of photovoltaic (PV) modules is the power drop that occurs as the silicon temperature increases due to the characteristics of the crystalline silicon used in a solar cell. To overcome this reduction in power, module surface cooling using water circulation was employed. The model performance was then conceptually evaluated and experimentally verified. A transient model was developed using energy balances and heat and mass transfer relationships from various other sources to simulate the surface cooling system. The measurements were in good agreement with the model predictions. The maximum deviation between the measured and predicted water and silicon temperature differed by less than 4 °C. The maximum power enhancement in response to the cooling was 11.6% when compared with a control module. The surface cooling system also washed the module surface via water circulation, which resulted in an additional power up of the PV module in response to removal of the particles that interfere with solar radiation from the surface of the PV module. Accordingly, the cooling system could reduce maintenance costs and prevent accidents associated with cleaning. In addition, the increase in cooling water temperature can serve as a heat source. The system developed here can be applied to existing photovoltaic power generation facilities without any difficulties as well.

Wheat straw is a potential feedstock in biorefinery for sugar production. However, the cellulose, which is the major source of sugar, is protected by lignin. Ozonolysis deconstructs the lignin and makes cellulose accessible to enzymatic digestion. In this study, the change in lignin concentration with different ozonolysis times (0, 1, 2, 3, 5, 7, 10, 15, 20, 30, 60min) was fit to two different kinetic models: one using the model developed by Garcia-Cubero et al. (2012) and another including an outer mass transfer barrier or "cuticle" region where ozone mass transport is reduced in proportion to the mass of unreacted insoluble lignin in the cuticle. The kinetic parameters of two mathematical models for predicting the soluble and insoluble lignin at different pretreatment time were determined. The results showed that parameters derived from the cuticle-based model provided a better fit to experimental results compared to a model without a cuticle layer.

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