Joseph Khedari

Study of natural ventilation of houses by a metallic solar wall under tropical climate

Heat removal from habitation was studied by using a metallic solar wall (MSW) at Bangkok. The MSW consists of a glass cover, air gap, black metallic plate and insulator made of micro-fiber and plywood. It was found that the MSW with 14.5 cm air gap and 2 m2 of surface area (H×W: 2×1 m) produced the highest air mass flow rate of about 0.01–0.02 kg s−1. Room temperature during tests was near to ambient air, ensuring human comfort resulting from the ventilation produced by the MSW. Comparison between simulated and experimental results showed a good accord, therefore the numerical model is valid. Thus, it can be used to evaluate the long-term reduction of heat transfer into the habitation.

New lightweight composite construction materials with low thermal conductivity

Abstract This paper presents an initial investigation on the use of a new lightweight construction material, composed of cement, sand and fiber of waste from young coconut (Cocos nucifera) and durian (Durio zibethinus). Thermal conductivity, compressive strength and bulk density were investigated. The experimental investigation reveals that the addition of these fibers reduces the thermal conductivity of the composite specimen and yield a lightweight. The composite satisfies the basic requirement of construction materials, and they could be used for walls and roofs. Thus, the potential for development, therefore, seems to be very promising. Finally, apart from saving energy consumption for the building, the proposed materials offer an alternative option to dispose waste of fruit industry.

Ventilation impact of a solar chimney on indoor temperature fluctuation and air change in a school building

Abstract The aim of this research was to investigate, experimentally, both the feasibility of a solar chimney to reduce heat gain in a house by inducing natural ventilation and the effect of openings (door, window and inlet of solar chimney) on the ventilation rate. The study was conducted using a single-room school house of approximately 25 m 3 volume. The southern wall was composed of three different solar chimney configurations of 2 m 2 each, whereas, the roof southern side included two similar units of 1.5 m 2 each of another solar chimney configuration. Those configurations were built by using common construction materials. Experimental observations indicated that when the solar chimney ventilation system was in use, room temperature was near that of the ambient air, indicating a good ability of the solar chimney to reduce houses heat gain and ensuring thermal comfort. The air change rate varied between 8–15. Opening the window and door is less efficient than using solar chimneys, as temperature difference between room and ambient was higher than that obtained with solar chimneys.

New insulating particleboards from durian peel and coconut coir

The development of new particleboards from tropical fruit peels with low thermal conductivity as a component of construction panels for energy conservation of building is the main purpose of this study. Durian (Durio zibethinus) peels and coconut (Cocos nucifera) coir fibers were used as the raw material to manufacture particleboards. Two main parameters were investigated namely binder types, (UF 12%, PF 6% and IC 3%) and board density. In general, the effect of adhesive type on the properties of boards was not obvious whereas that of the density was more significant on most properties of boards. Experimental investigation indicated that the mechanical strength of all boards such as modulus of rupture and modulus of elasticity increased with increasing board density, but it is still rather low. However, this decreased the dimensional stability, measured in term of thickness swelling, and thermal conductivity as well. Finally, as the raw materials are agriculture waste, manufacturing particleboards is therefore an economic and interesting option. Such natural particleboards with a low thermal conductivity could be utilized for specific applications as in insulating ceiling and walls.

Experimental study of a roof solar collector towards the natural ventilation of new houses

The paper discusses the possibility of offering thermal comfort in new housing built in European style and situated in a hot and humid climate, without inducing mechanical energy cost, by means of a constructive element: the Roof Solar Collector (RSC). With this RSC it is possible, on the one hand, to minimize the fraction of the solar flux absorbed by the dwelling (insulation) and, on the other hand, to induce a natural ventilation which improves its thermal comfort. The influence of length and tilt angle of the RSC and local constructing materials used on the performance of the RSC is studied experimentally. The results of the study were that the appropriate materials of the roof solar collector, with regard to the improved natural ventilation, should be CPAC Monier concrete tiles on the outer side and gypsum board on the inner one. The optimum length of roof solar collector must be shorter on the order of 100 cm and tilted at 30°. The induced natural ventilation rate was about 0.08–0.15 m3s−1 m−2.

Thailand ventilation comfort chart

Abstract The paper presents a ventilation comfort chart that has been developed under Thailand climate and using Thai volunteers. 183 male and 105 female college-age subjects were exposed to different thermal conditions in order to investigate the effect of air velocity on thermal comfort in ventilated “non-conditioned” spaces. To this end, commercial electric fans were used to control the air velocity near the subjects. The air velocity varied between 0.2 and 3 m/s. Room conditions varied between 26°C and 36°C (D.B.T.) and 50–80% relative humidity. Thermal sensation vote was recorded through a questionnaire. The Predicted Mean Vote was used to determine the indoor neutral temperature. This developed chart could be used to design ventilation system for offices and classrooms.

Field measurements of performance of roof solar collector

To reduce the mechanical cooling energy cost of new housing built in a hot and humid region, the design should maximize the natural ventilation and minimize the fraction of sun energy absorbed by a dwelling. This objective is accomplished by using the roof structure to act as a solar collector. The roof solar collector design (RSC) used CPAC Monier concrete tiles and gypsum board. Two units of RSC were integrated in the roof structure of the school solar house. The effects of air gap and openings of RSC on the induced air flow rate and thermal comfort were studied experimentally.

New configurations of a roof solar collector maximizing natural ventilation

Abstract The paper discusses the performance of a construction element: the Roof Solar Collector (RSC) with regard to maximizing the rate of induced natural ventilation, which contributes to the improvement of indoor thermal comfort of houses. The RSC configuration was made by using modern materials: CPAC monier concrete tiles on the outside and gypsum board on the inside. The comparison of numerical results with available experimental data validated the developed model. The effect of RSC parameters, mainly tilt angle and length, was analyzed numerically. Finally, new configurations of RSC were proposed and discussed.

Thailand climatic zones

This research was aimed to classify the climatic conditions of different locations in Thailand into zones of relatively similar ambient conditions. This classification is extremely useful to the building design for a wide range of objectives such as energy conservation, residential thermal comfort, outdoor design conditions, etc.

The Potential of Waste Heat Thermoelectric Power Generation From Diesel Cycle and Gas Turbine Cogeneration Plants

This study assesses the potential of waste heat thermoelectric power generation for diesel cycle and gas turbine cogeneration in the manufacturing industrial sector in Thailand. To this end, data from more than 27,000 factories from different sectors, namely, chemical product, food processing, oil refining, palm oil mills, petrochemical, pulp and paper rice mills, sugar mills, and textiles, were used. The potential of waste heat thermoelectric power generators was analyzed using an annual cost method based on stack exhaust from a cogeneration system for different operation hours, system life spans, bank interest rates, system prices, maintenance costs, depreciation, internal rates of return, and electricity buy back rates sold to the grid line. Gas turbine and diesel cycle cogeneration systems produced electricity estimated at 33% and 40% of fuel inmput, respectively. The useful waste heat from stack exhaust of cogeneration systems was estimated at 20% for gas turbine and 10% for diesel cycle. The corresp...This study assesses the potential of waste heat thermoelectric power generation for diesel cycle and gas turbine cogeneration in the manufacturing industrial sector in Thailand. To this end, data from more than 27,000 factories from different sectors, namely, chemical product, food processing, oil refining, palm oil mills, petrochemical, pulp and paper rice mills, sugar mills, and textiles, were used. The potential of waste heat thermoelectric power generators was analyzed using an annual cost method based on stack exhaust from a cogeneration system for different operation hours, system life spans, bank interest rates, system prices, maintenance costs, depreciation, internal rates of return, and electricity buy back rates sold to the grid line. Gas turbine and diesel cycle cogeneration systems produced electricity estimated at 33% and 40% of fuel inmput, respectively. The useful waste heat from stack exhaust of cogeneration systems was estimated at 20% for gas turbine and 10% for diesel cycle. The corresponding net power generation is about 100MWe.