Fabrication and Simulation of TE Modules for a Feasibility Study on Harvesting Solar Heat Energy from Roof Tiles

A novel roof tile thermoelectric generator(RT-TEG)was used to harvest electrical energy from a solar heat source.The RT-TEG was fabricated and simulated by flat and curved thermoelectric modules consisting of p-n junctions of p-Sb_(2)Te_(3) and n-Bi_(2)Te_(3),with an Al_(2)O_(3) substrate at the top and bottom for heat absorption and heat rejection.The RT-TEG was installed in a roof tile to act as a generator.The electrical voltage and power values of the curved thermoelectric modules were higher than those of the flat thermoelectric module by 0.44 V and 80 mW,at a temperature difference(ΔT)of 100 K.In field tests,the RT-TEG produced a maximum electrical voltage of 33.70 mV and an electrical power of 46.24μW atΔT~7 K under a load resistance of 1Ωunder good sunshine at 13.00 hours.The energy conversion efficiency of RT-TEG was found to be 2.24×10^(−4).

Effects of porosity,dry unit weight,cement content and void/cement ratio on unconfined compressive strength of roof tile waste-silty soil mixtures

One of the conventional ways to improve the mechanical behavior of soils is to mix them with cementing agents such as cement, lime and fly ash. Recently, introduction to alternative materials or sub-products that can be adopted to improve the soil strength is of paramount importance. Therefore, the present study aims to investigate the effects of porosity(h), dry unit weight(gd) of molding, cement content(C)and porosity/volumetric cement content ratio(h/Civ) or void/cement ratio on the unconfined compressive strength(quor UCS) of silty soileroof tile waste(RT) mixtures. Soil samples are molded into four different dry unit weights(i.e. 13 kN/m^3, 13.67 kN/m^3, 14.33 kN/m^3 and 15 kN/m^3) using 3%, 6% and 9%cement and 5%, 15% and 30% RT. The results show that with the addition of cement, the strength of the RT esoil mixtures increases in a linear manner. On the other hand, the addition of RT decreases quof the samples at a constant percentage of cement, and the decrease in porosity can increase qu. A dosage equation is derived from the experimental data using the porosity/volumetric cement content ratio(h/C_(iv)) where the control variables are the moisture content, crushed tile content, cement content and porosity.

SEMI-TIERED HOUSING FOR LATERITE EARTH SLOPING LANDS-A SUSTAINABLE SOLUTION WITH ALTERNATIVE MATERIALS AND METHODS

Increased demand for affordable housing and the limited availability of flat terrain for its construction are two major problems facing the provision of houses of acceptable quality in many countries around the world.There is limited research integrating the utilization of a stepped approach to sloping terrain with appropriate housing models to minimize slope instability potential.This paper introduces a new semi-tiered housing model where the footprint of the house is located on tiers prepared with short vertical cuts of 1.5-2m.Such vertical cuts are found to be stable with laterite soil which is a commonly available type of soil in the tropics.The excess soil generated from cut material was transformed into cement stabilized rammed earth,which is a cost effective material with low embodied energy.This is an ideal candidate for the construction of retaining walls and foundations,and such applications are demonstrated with adequate details.Further,many other types of sustainable building materials are highlighted with a case study of this housing model in a scheme of 13 housing units in Sri Lanka.The attention to detail required in construction and the applicability of alternative building materials and methods to improve the sustainability of such houses have been discussed in detail.These semi-tiered houses have the potential to address many of the current construction challenges.

CFD analysis and experimental comparison of novel roof tile shapes

In tiled pitched roofs,a ventilated layer reduces the heat transfer between tiles and roof structure by means of natural and forced convection,thereby also reducing the cooling energy requirement.This effect could be enhanced by increasing the air permeability between the tiles by means of novel tile shapes,as proposed by the HEROTILE European project(UFE14 CCA/TT/000939),of which this work presents the preliminary analysis supporting the new tile designs.Using an experimental rig,the air pressure difference and the volumetric flow rate between tiles have been measured for an existing Portoghese tile design over a range of pressures.Then,in older to understand the air flows under different conditions,a three-dimensional computational fluid dynamics(CFD)model has been implemented to recreate the full geometry of the rig.The model was calibrated against the aforementioned experimental results,and ran with boundary conditions simulating different wind directions.Even in the low velocities typical of average local wind patterns,the fluid dynamic problem remains complex because of the geometry of the gaps between the tiles.analytical relationship between pressure drop and flow rate,taking into account the open area.The results have shown how the wind direction affects the air permeability and,therefore,important insights have been gathered for the design of novel tiles.