Heat transfer from a buried pipe has been a subject of great interest due to its many important engineering applications, which include the underground pipelines for oil and gas transport and the power cables. The problem considered in the present study has applications related to a radiant underfloor heating system in residence and industry. In the existing literature, heat transfer from a buried pipe has been considered for various heat transfer modes and configurations. For example, analytical solutions are readily available for heat conduction from one single cylindrical heat source or multiple heat sources, and the heat transfer results are often expressed in terms of the conduction shape factor. As for heat convection from an array of pipes, most of the existing studies have been focused on external crossflow with forced convection from a bundle of pipes with either aligned or staggered pipe arrangement. This area of research has received much attention due to its important industrial applications in the design of boilers and heat exchangers. On the other hand, studies involved natural convection from an array of pipes are relatively limited. The problem considered in the present study is related to the simulation of underfloor piping systems suspended in the joist space beneath the subfloor. Natural convective heat transfer from a row of horizontal heated pipes embedded in a closed cavity filled with air has been numerically examined in this study. A two-dimensional steady-state model has been developed using ANSYS Fluent for the numerical simulation. A parametric study has been performed to investigate the effects of pipe spacing, pipe depth and pipe temperature on the flow patterns and heat transfer rates. The heat transfer mechanism from the heated pipes to the top surface of the air-filled cavity is revealed through the plots of streamlines and isotherms. The present numerical model has been developed and validated using a parallel experimental study. From the radiant underfloor heating application perspective, the results showed that a radiant heating system with pipes embedded at a shallow burial depth and placed closer together resulted with a more desired surface temperature distribution.

Thermal insulation is a very important way to save energy in buildings or any other thermal application. For buildings, thermal insulation minimizes the heat transfer rate between a conditioning zone and its surroundings. For thermal applications, such as thermal storage tanks, it keeps heat or cold stored for later use. The current study is part of a project investigating thermal insulators made from cheap natural, organic and waste materials. The thermal conductivity of six different specimens of thermal insulator, made from used water cotton filter, chicken feather, walnut shell, sunflower seed husk, sawdust and ash, was measured experimentally. Industrial white glue was used as a binder to prepare the specimens. The sawdust and ash, of which the thermal conductivities are known, were chosen to validate the geometry of the specimens as well as the measurements of the testing device. The results showed that all types provide good thermal resistance performance. In particular, the insulator made from used water cotton filter was the best. It provided 0.0277 W/m k, which is a very practical value of the thermal conductivity in thermal insulation applications. This study will contribute significantly to sustainability by recycling wastes or using abundant natural and cheap materials in thermal insulators.

Any airconditioned zone must be thermally insulated from its surroundings to maintain the desired temperature. Thermal insulators thus play a significant role in reducing heat transfer between airconditioned areas and their surroundings to save energy. Thermal insulators are usually made from materials with low thermal conductivity, and to reduce the cost of such insulators, this study investigated the use of waste organic materials as thermal insulators. This study is the second part of a project that aims to achieve an optimised insulator from both the thermal and economic perspectives. To achieve this, the heat conductivity of five different samples made from hair, grass, date seed, and date palm fibre were examined. The all samples were made with industrial white glue as a binder. The heat flow method was employed to determine their thermal conductivity, with results that showed that all samples offered thermal resistance to heat transfer in the range 0.0530 to 0.1068 W/mK. The best thermal resistance was provided by the sample made from hair and fibres. The current study supports sustainability by encouraging the use of waste organic materials in thermal insulators.

Radiant floor heating systems have become popular due to their advantages over conventional heating systems in residential, commercial and industrial spaces. They are also used for snow and ice melting and turf conditioning applications. This paper presents a general study focuses on the design of radiant floor heating systems and investigates the effect of design parameters such as pipe spacing (ranging from 4 in. to 12 in.), pipe depth (ranging from 2.5 in. to 6.5 in.) and pipe temperature (45 °C, 65 °C and 85 °C) on the performance of radiant floor heating system embedded in different mediums (air, gravel and sand). The experimental results showed that a radiant heating system with pipes embedded at a shallow burial depth and placed closer together resulted with a more desired floor temperature distribution. The average floor temperature was also higher when the piping system was embedded in an air-filled space instead of a porous medium such as gravel or sand.

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