Thermal Simulation Method Research Articles

Spectral calculation of the thermal performance of a solar pond and comparison of the results with experiments

This paper deals with a method and the result of the spectroscopic calculation on heat balance of a salt-gradient solar pond under the conditions of spectral solar radiation. Furthermore, reflection of the ray incident upon the surface of the pond water, refraction of the rays within the salt-water layer and diffusion of salt in the pond water are considered. On the other hand, in order to make a clear mechanism of the heat collection and heat storage of the solar pond, we conducted an indoor experiment and a numerical analysis on a small scale model of the salt-gradient solar pond with 2 m 2 surface area and 1.6 m depth, under the incident rays from a Xe-lamp solar simulator. According to the above experimental analysis, we made a simulation model of thermal performance for a solar pond and carried out the calculation from the heat balance. We found that the simulation calculations correspond well to the experimental results, so that our thermal simulation model and method might be correct. We also did the thermal calculation by changing the incident rays from a Xe-lamp into natural ray (Moon’s spectrum) and Halogen lamp. As a result, it was found that the temperature distributions in the solar pond were notably different due to spectral characteristics of the incident ray. Therefore, the spectroscopic consideration for thermal performance of any solar pond is necessary to obtain a correct solution under the spectral incidence with special wavelength distributions.

Tracing the thermal behavior of ICs

Today's increased power and packaging densities demand designers' attention to the effects of heat on ICs. The authors review thermal and electrothermal simulation and measurement methods, thermal package characterization, and the concept and techniques of design for thermal testability.

Adaptive-Implicit Method in Thermal Simulation

Summary An adaptive-implicit method (AIM) for thermal simulation that provides different degrees of implicitness in various gridblocks is discussed. A special treatment of flow terms during appearance or disappearance of any particular phase is critical. This treatment creates a more stable Jacobian matrix, especially in cases where an implicit block is downstream of an explicit neighbor. The maximum eigenvalue of a local amplification matrix, which is related to a dimensionless front velocity, determines the switching between implicit and explicit treatment. The switching, which is automatic and problem-independent, is superior to classical threshold switching based on the magnitude of changes of key reservoir variables. Results from the simulation of several thermal recovery processes are presented. The saving in computer time over a fully implicit method ranges from 34 to 62%. The maximum savings can be achieved in the simulation of large field-scale problems in which the fronts are moving fairly slowly.

Estimation of steady state ground losses from earth coupled structures by simulation

A thermal simulation method for estimating the ground losses from earth coupled structures has been described. The accuracy of the method has been evaluated by comparing the experimental results obtained for a sphere with the corresponding analytical results. The method has been used to determine the shape factor, which can be used to evaluate the heat loss to the ground for (i) slab-on-grade buildings, (ii) a sunken cylindrical structure, and (iii) sunken and buried parallelepiped structures for different ratios of their dimensions.

ブラックパネル温度に基づく熱劣化予想マップ : 屋外での熱劣化環境の定量化(その1)

Heat is recognized as general degradation agent of most building materials. Therefore quantification of thermal degradation is essentialy important to discuss the durability. Based on the theory of chemical reaction rate, author proposed a thermal degradation simulation method to predict the service life of building materials. Introducing black-panel temperature, the property change of model material was estimated. The thermal degradation simulation method is consist of following steps. 1) From thermal aging test at several constant temperature, degradation material constants are obtained. Some supposed constants were used in this paper. 2) Black-panel temperature, which is an index of thermal degradation environment, is measured in outdoor and the relation between daily equivalent black-panel temperature and meteorological elements are analysed. The daily equivalent black-panel temperature in various area can be estimated by the observed meteorological data. 3) The property change of material can be calculated using daily equivalent black-panel temperature day by day, and the obtained results are plotted on a map.