heat transfer

Experiments and computer simulations were conducted to evaluate the performance of radiant barriers under three different insulation levels in residential applications. The experiments were conducted in central Texas, USA using side-by-side comparisons in which two houses, with identical floor plans and thermal profiles, were used. The houses were instrumented, calibrated, and their heat transfer rates across the ceilings were measured and recorded. A heat and mass transfer model was used to run the computer simulations.

This paper presents a numerical model to investigate the foundation heat transfer from conditioned basements when the ground is composed of multilayered strata with different thermal properties. The model is used to determine the thermal performance of several basement insulation configurations under both steady-state and transient conditions. It is found that the nonhomogeneity of the soil significantly affects the heat transfer from uninsulated basement walls rather than the basement floor or insulated basement walls.

This paper outlines the methods and results of a four-year project that measured heat flows through two uninsulated slab-on ground floors on nominally wet soils. One floor was on peat soil, the other on clay, and water table depths were 0.5 m to 1.0 m through most of the year. Heat fluxes were measured over the whole floor using heat flux transducers (HFT) at the concrete floor surface, and temperatures were measured by thermocouple, continuously for four years. The soil conductivities and soil temperatures were measured daily at 11 positions near one edge of the floors.

A large-scale model of an attic construction has been built in a climatic chamber. The purpose of the attic test model is to investigate hear transfer-in particular, heat transfer by convection-in loose-fill attic insulation. The influence of a number of factors on heat flows can be investigated using the attic test model; for example, insulation thickness, attic ventilation, ceiling construction, roof slopes, and the quality of installation workmanship. The heat flow through the attic ceiling construction is measured with a metering box.

The study was to test five units used in single house mechanical ventilation systems with heat recovery. Tests were made according to CEN project prepared by CEN TC 156/WG2/AH7 including air tightness, pressure-airflow's curves and temperature ratios. A full test on frost and condensation was also realised on one unit to determine the influence of these parameters on performances. Test results, influence of wet or dry conditions and main conclusions for using these results in dimensioning, will be given.

Convective transfers mainly determine the energy and mass balances which regulate the micro-climate inside a greenhouse. Air flow and temperature patterns induced by natural ventilation through greenhouse roof openings are only considered here. Flow visualizations were performed on a half scale test cell simulating the absorption of solar radiation at the floor surface of a single-span greenhouse. Temperature and air flow patterns were observed in a steady regime i) with a single sided roof vent and ii) with two symmetrical one.

The purpose of this work is to evaluate the air infiltration through the high buildings and in the same time to determine the exchange of the air between the rooms and the influence of the heat transmission for these exchanges. The method of approach for this problem is a network model. This is a grid system in which the nodes are the rooms or zones of the building and the connection between two nodes simulates a flow path of a given resistance. It was built a computer program for predicting the interactions between different zones which was applied for a given case of a building.

Low energy buildings should satisfied two main tasks: to assure a low energy use and provide an excellent residence comfort. The building envelopment elements, especially the transparent one, have major influence on both tasks. The paper presents research results of heat transfer and fluid flows through double pane window with tight, opaque insulation screen. The insulation screen was installed in such a way, that a semi open air gap was formed. An air gap is connected with the building interior through an opening on the bottom and with exterior through siphon at the top.

As the thermal sensation of humans depends directly on heat transfer characteristics between the body surface and the surrounding environment, it is very important to clarify the heat transfer characteristics of a human body surface in detail. This paper describes a combined numerical (NOTE I) simulation system of airflow, thermal radiation and moisture transport based on a human thermo-physiological model used to examine the total (sensible + latent) heat transfer characteristics of a body surface. The human body is assumed to be naked (NOTE 2).