Naris Pratinthong

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.

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.

The Modified Trombe Wall: A simple ventilation means and an efficient insulating material

SYNOPSIS This paper discusses the feasibility of reducing heat transferred into houses (insulation effect) and inducing natural ventilation by using a modified Trombe wall (MTW) under ambient conditions in Bangkok. It consists of a masonry wall, air gap and a gypsum wall which are common construction materials. It was found that the MTW with 2 m2 of surface area, 14 cm air gap and dark in colour induced the highest natural ventilation rate, about 20–90 m3.h−1. The light colour of the wall induced the lowest rate, but was still significant for the ventilation of houses. With such air flow rates, there is little potential to induce sufficient ventilation to achieve thermal comfort of the house, however, the proposed configuration of the MTW should be recommended for constructing new houses, mainly, because of its high insulation effect.

Natural ventilation of houses by a Trombe wall under the climatic conditions in Thailand

SYNOPSIS The paper discusses the feasibility of using the well known Trombe wall to ventilate houses under Bangkok ambient conditions. The effects of air gap and wall height on the induced ventilation were investigated experimentally. A numerical model was also developed that could be a useful tool for designing such a system under different ambient conditions.

Field study using the ground as a heat sink for the condensing unit of an air conditioner in Thailand

This paper reports on an investigation of the feasibility of using earth to absorb the heat normally rejected into the atmosphere by the condensing unit of a conventional air conditioner. To this end, a copper tube of about 67 m in length was buried at a depth of 1 m underground, where the temperature was constant at about 27°C year round. The copper coil of an air type condenser is about 22 m long. For the buried condenser, the R-22 refrigerant requirement was 5.8 kg as compared with 1.2 kg for the air condenser system. It was found that with this modified condensing unit, the coefficient of performance (COP) was much higher than that of a conventional one: it varied between 7.1 (daytime) and 8.1 (nighttime), compared to 2.8 and 3.1, respectively. The ground temperature near the buried copper coil did not increase, thus demonstrating the ability of the soil to dissipate the absorbed heat into the ground. Consequently, there is a high potential for contributing to environmental protection by using the ground as a heat sink. The elimination of the condensing fan is an additional advantage of the buried condenser system.

Domestic hot water system combining solar and waste heat from thermoelectric air-conditioner

SYNOPSIS This paper investigates the performance of a new hybrid domestic hot water system that combines solar energy with waste heat from a thermoelectric (TE) air-conditioner. To this end, 30 TE modules model no. TEC1-12704 (module specifications: 40 × 40 mm, maximum operating voltage and current: 13.5 VDC and 4.4 Amp) were used. The collector/storage tank capacity was 120 litres. The volume of the testing room for cooling was 2.5 m3. Investigations were undertaken by varying the voltage to the thermoelectric module (50, 100, 150 VDC), water mass flow rate and air velocity passing through the TE heat exchangers: 10, 15 l/min and 2.5, 5 m/s, respectively. It was found that this system can heat up the 120 litres to 50°C within 2 hours. The cooling capacity was 176 W. After that, the cooling capacity decreased as a result of the increase of water temperature returned from the tank and circulated through TE water/solid heat exchanger. Finally, under design consideration used in this study, the optimum conditions for operating the hot water production and cooling as well are: 100 VDC, water flow rate of 15 l/min and air velocity at 2.5 m/s. The corresponding highest coefficient of performance of the hybrid system is about 3.12.

NLARX Model Identification for Grid Tied Inverter Using Genetic Algorithm

This research studies the parameter identification for establish the model of inverter control system which has grid-connected in distributed power systems. Identification is a method of measuring the mathematical description of a system by processing the observed inputs and outputs of the system. The model developed is based on nonlinear autoregressive with exogenous input (NLARX) for simulate the inverter control system which has grid-connected in distributed power systems. To analyze the model, we use one, three and five steps ahead analysis technique which is the tool in mathematical model analysis for model categories of NLARX. In this research, we present comparative analysis of the model using NLARX in 3 different categories that is wavelet network, tree partition network and sigmoid network. The simulation results show that the optimal category of NLARX is sigmoid network which has one, three and five steps ahead value is equal to 97.01, 91.50 and 88.90 percent respectively from output model and the measured output from the validation data set from grid tied inverter mathematical modelling using genetic algorithm. This optimal model can be used to simulate for analyze trends of the output data which can represent for the real system.