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Abstract-Four numerical models have been built for the simulation of the thermal yield of a combined PV-thermal collector: a 3D dynamical model and three steady state models that are 3D, 2D and 1D. The models are explained and the results are compared to experimental results. It is found that all models follow the experiments within 5% accuracy. In addition, for the calculation of the daily yield, the simple 1D steady state model performs almost as good as the much more time-consuming 3D dynamical model. On the other hand, the 2D and 3D models are more easily adapted to other configurations and provide more detailed information, as required for a further optimization of the collector. The time-dependent model is required for an accurate prediction of the collector yield if the collector temperature at the end of a measurement differs from its starting temperature.

The metabolic and temperature response to mild cold were investigated in summer and winter in a moderate oceanic climate. Subjects were 10 women and 10 men, aged 19-36 years and BMI 17-32 kg/m2. Metabolic rate (MR) and body temperatures were measured continuously in a climate chamber with an ambient temperature of 22 degrees C for 1 h and subsequently 3 h of 15 degrees C. The average metabolic response during cold exposure, measured as the increase in kJ/min over time, was significantly higher in winter (11.5%) compared to summer (7.0%, P < .05). The temperature response was comparable in both seasons. The metabolic response in winter was significantly related to the response in summer (r2 = .47, P < .001). Total heat production during cold exposure was inversely related to the temperature response in both seasons (summer, r2 = .39, P < .01; winter r2 = .32, P < .05). In conclusion, the observed higher metabolic response in winter compared to summer indicates cold adaptation. The magnitude of the cold response varies, but the relative contribution of metabolic and temperature response was subject specific and consistent throughout the seasons, which can have implications for energy balance and body composition.

Hair loss is a feared side effect of chemotherapy treatment. It may be prevented by cooling the scalp during administration of cytostatics. The supposed mechanism is that by cooling the scalp, both temperature and perfusion are diminished, affecting drug supply and drug uptake in the hair follicle. However, the effect of scalp cooling varies strongly. To gain more insight into the effect of cooling, a computer model has been developed that describes heat transfer in the human head during scalp cooling. Of main interest in this study are the mutual influences of scalp temperature and perfusion during cooling. Results of the standard head model show that the temperature of the scalp skin is reduced from 34.4 • C to 18.3 • C, reducing tissue blood flow to 25%. Based upon variations in both thermal properties and head anatomies found in the literature, a parameter study was performed. The results of this parameter study show that the most important parameters affecting both temperature and perfusion are the perfusion coefficient Q 10 and the thermal resistances of both the fat and the hair layer. The variations in the parameter study led to skin temperature ranging from 10.1 • C to 21.8 • C, which in turn reduced relative perfusion to 13% and 33%, respectively.

Laser-Doppler velocity measurements were performed on the entry flow in a 90" bend of circular cross-section with a curvature ratio a / R = 1/6. The steady entry velocity profile was parabolic, having a Reynolds number Re = 700, with a corresponding