Ong kok seng

Universiti Tunku Abdul Rahman | utar · Department of Industrial Engineering

This study investigates the effect of inclination angle of a flat plate solar air collector in Kampar, Malaysia. Flat plate solar air collectors have been investigated since the early 1950s for air heating and crop drying. Their performances under natural convection air cooling are very similar to a photovoltaic (PV) panels for power production. A...

The temperature of a PV panel rises during operation which affects its power output. A PV panel is similar to a flat plate solar collector. This paper presents a simple theoretical heat transfer resistance model and a solution procedure to predict the absorber plate surface temperature of the solar collector. The model consisted of a rectangular cr...

Electronic devices need to be cooled efficiently. Phase change material (PCM) could be incorporated into a conventional fin heat sink (FHS) for such a purpose. This paper reports experimental results obtained on the thermal performances of four FHSs fabricated with different arrays and numbers of hollow aluminium pin fins with various lengths and d...

In the present study, a numerical model of photovoltaic thermal (PV/T) system using alumina (Al 2 O 3 ) nanofluid, and pure water are used as working fluid. The proposed PV/T model consists of parallel riser tubes that are connected to two header tubes and it is attached to an absorber plate to simulate the conduction and convection heat transfer m...

Purpose As suggested in many previous studies, good thermal comfort and indoor air quality (IAQ) played a significant role in ensuring human comfort, health and productivity in buildings. Hence, this study aims to evaluate the thermal comfort and IAQ conditions of open-plan office areas within a green-certified campus building through a post occupa...

PV panel installation on rooftops is increasing all around the world. The negative effect of the temperature increment on the performance of the PV panels is known. This study aims to evaluate the effect of the gap between the panels and rooftop on the effectiveness of free natural convection to pick up heat from the PV panel. The experimental and...

Solar energy can be harnessed to produce thermal and electrical energy. With regard to this, Solar Photovoltaic (PV) is a well-known solar technology that is used to convert from solar energy to electrical energy. Nevertheless, Solar PV efficiency drops as the solar PV panel temperature increases. Another way to generate electricity from the solar...

Main barriers for installation of conventional solar water heating system (SWHS) are requirement of large installation area and heavy weight of the heat storage tank consisting water. A storage tank with minimum capacity of 230 liters are needed for household usage and this tank when empty can weigh up to 100 kg while a filled tank could weigh up t...

Thermoelectric Generator (TEG) provides unique advantages as compared to other heat engines as it is capable to convert heat to electricity directly without having any moving parts. Furthermore, TEG is compact, simple and noiseless and requires very minimal maintenance. This paper presents an experimental and analytical study of a model consisting...

Purpose The purpose of this paper is to introduce a practical integrated overall equipment effectiveness (OEE) framework that encompasses the core characteristics of OEE. Design/methodology/approach The paper reviewed the backgrounds of OEE and improvement frameworks and explored the limitations. An integrated OEE framework was developed by synerg...

The aim of this work is to determine the effect of coating and blending composition of myristic acid (MA) with polymethyl methacrylate (PMMA) on the latent heat and thermal stability of phase change material (PCM). Form‐stable PCM (FSPCM) was prepared by blending MA with PMMA and then coating with nitrile butadiene rubber (NBR) and polyacrylic acid...

Light absorptive polymeric form-stable composite phase change tablet (RGO-PARB/MA) was prepared by dip-coating myristic acid (MA) tablets into layers of polymer coating solution with reduced graphene oxide (RGO). RGO serves as light absorptive material to harvest sunlight and converts it to thermal energy to be stored in PCM. Ultraviolet (UV)-Visib...

Phase change materials (PCMs) are promising for latent heat thermal energy storage (LHTES) applications. However, encapsulation of PCMs is needed to prevent them from leaking before being utilized in energy storage system. The main aim for this work is to produce form stable phase change material (FSPCM) that can withstand volume change of PCM duri...

The flow developing in water-filled vertical and loop thermosyphons fabricated from glass tubes were recorded using a digital camera. The evaporator section of each thermosyphon was immersed into an electrically-heated water bath. The condenser section was cooled with a fan. Transient flow patterns were observed and recorded from start until the wa...

Phase change material (PCM) has attracted much interest in thermal energy storage (TES) applications due to its large heat storage capacity. The major drawback of PCM is the leakage of container, attributed by volume change during phase transition. Thus, the aim of this work is to produce form stable phase change material (FSPCM) with no leakage. F...

Heat pipes (HPs) are very efficient heat exchangers. Experiments were conducted to determine the thermal performances of two sintered heat pipes each 1780 mm long x 8 mm OD and 580 mm long x 10 mm OD under power inputs from 30 to 120 W and inclinations from −90° to +90° to the horizontal. Results showed that they performed better with the evaporato...

Purpose: Existing productivity improvements activities such as inventory buffer, overall equipment effectiveness (OEE) and total productive maintenance (TPM) do not analytically associate the throughput shortage with process parameters. The paper aims to develop and test an integrated model to recover the throughput shortage through process paramet...

Over the last decades, the science of solar cells has been substantially soared; however, the existence philosophy needs to follow almost the same mechanism due to the known limitations. Building upon this fact, until now, several generations of solar collectors have been introduced to the field of renewable energies. This current study reports an...

In the present study, the fluid flow and heat transfer characteristic of microchannel heat sink with microfins are studied numerically at Reynold number ranging from 400 to 1200. The influence of microfins on the Nusselt number and pressure drop are investigated. Five different types of microfins namely cylindrical microfins (Case A), diverge cylin...

Downward lighting light-emitting diodes require cooling with cylindrical fin heat sinks to be mounted on top and cooled under natural convection air cooling mode. Performance simulation would involve specification of the heat transfer coefficient. Numerous methods are available to simulate the performance of conventional plate fin heat sinks includ...

This article is focused on thermoelectric cooling (TEC) and thermoelectric power generation (TEG). Detailed theoretical modeling and characterization were presented with the key performance highlighted. Heat transfers from heat sinks on both hot and cold surfaces of the thermoelectric models were discussed and measures to enhance and increase heat...

This article is focused on thermoelectric cooling (TEC) and thermoelectric power generation (TEG). Detailed theoretical modeling and characterization were presented with the key performance highlighted. Heat transfers from heat sinks on both hot and cold surfaces of the thermoelectric models were discussed and measures to enhance and increase heat...

Failure mode effect and analysis (FMEA) is a well-known methodology for improving operational performance, such as the quality, cost, and delivery time of a product, process, or system. However, the success of FMEA in operational performance cannot be quantified at present. The risk priority number (RPN), which is the only indicator of FMEA, has no...

Solar water heater (SWH) incorporating solid-liquid organic phase change materials as thermal energy storage (TES) have attracted attention since 1970s. However, the development of these PCMs to practical application had been restricted by its low thermal stability and thermal conductivity. Recently many type of composite solid-liquid organic PCMs...

The aim of this study is to simulate and investigate the heat transfer phenomenon of light emitting diode packages. The performance of FR-4 and MCPCB dielectric materials with thermal conductivity of 0.3 W/mK and 201 W/mK respectively are numerically compared. MCPCB material is found to be an effective base that holds 34.8 _C for an input power of...

The composite PCM was prepared by blending polymethyl methacrylate (PMMA) and myristic acid (MA) in different weight percentages. The MA and PMMA were selected as PCM and supporting material, respectively. As liquid MA may leak out during the phase transition, this study proposes the use of two coatings, namely a polyacrylic coating and a conformal...

In this study, reduced graphene oxide (RGO)/polymethyl methacrylate (PMMA) nanocomposites were prepared by employing in situ polymerization and solution blending methods. In terms of mechanical properties, RGO loading increased the Young’s modulus but decreased the elongation at break for RGO/PMMA nanocomposites. Tensile strength for solution blend...

Heat pipes are heat transfer devices capable of transferring large quantities of heat effectively and efficiently. A vapor chamber (VC) is a flat heat pipe. A novel VC with hollow condenser tubes embedded on the top of it is proposed. This paper reports on the experimental thermal performance of three VC devices embedded with hollow tubes and emplo...

A heat pipe is a passive heat transfer device capable of transferring a large quantity of heat effectively and efficiently over a long distance and with a small temperature difference between the heat source and heat sink. A heat pipe consists of a metal pipe initially vacuumed and then filled with a small quantity of fluid inside. The pipe is sepa...

Phase change material (PCM) is one of the most popular and widely used as thermal energy storagematerial because it is able to absorb and release a large amount of latent heat during a phase change process over a narrow temperature range. In this work, the form-stable composite PCM was prepared by blending of PMMA and myristic acid in different wei...

This paper reports an experimental investigation on a design of solar water heater system (SWH) employing evacuated tube heat pipe solar collectors (HPSCs) and a latent heat storage (LHS) tank. In this design, solar energy incident on the HPSC is collected and stored in the LHS tank via a heat pipe with fins attached to the condenser ends inside th...

An experimental investigation was conducted to evaluate the performance of a thermoelectric (TE) module fitted to a conventional fin heat sink with a similar sized heat source. Experiments were conducted with power inputs at 10Wand 20Wunder natural convection (NC) and forced convection (FC) air cooling. The results showed that the use of the TE mod...

An evacuated tube heat pipe solar collector was fitted with four thermoelectric modules and four water cooling jackets on the condenser side to produce electricity and hot water simultaneously. Each cooling jacket had six mini water-flow channels inside it. Solar heat was absorbed and collected by the evaporator section. Experiments were conducted...

Compact high powered semiconductor chips require greater heat dissipation and more effective thermal cooling systems have to be devised such as incorporating vapor chambers and thermoelectric. As a first step, the performance of two conventional fin heat sinks with flat metal base and an array of cooling fins on top are determined under force and n...

A fin heat sink (FHS) is a thermal heat transfer device employed to dissipate heat from a high temperature heat source to a lower temperature surrounding. A typical FHS consists of a flat metal base with an array of cooling fins on top. A problem normally encountered in thermal management of electronic packages is thermal heat spreading resistance...

The thermal performances of a R410A filled thermosyphon subjected to low power input from 40 - 100 W and evaporator wall temperatures between 25°C to 50°C with fill ratios between 0.50 - 1.00 and at different inclinations from 30° - 90° were investigated. The axial temperature distribution of the thermosyphon was found to be quite uniform at all te...

Abstract There are various methods employed to determine the performance of heat pipes and two-phase closed thermosyphons. Perhaps the most common method involves measuring the rate of heat transfer from the evaporator to the condenser section with a water cooled jacket surrounding the latter. This entails higher costs and requires extended testin...

The main advantage of latent heat thermal energy storage systems is the capability to store a large quantity of thermal energy in an isothermal process by changing phase from solid to liquid, while the most important weakness of these systems is low thermal conductivity that leads to unsuitable charging/discharging rates. Heat pipes are used in man...

The purpose of this paper is to model theoretically a solar hot water system consisting of an array of ETHPSC (evacuated tube heat pipe solar collectors) connected to a common manifold filled with phase change material and acting as a LHTES (latent heat thermal energy storage) tank. Solar energy incident on the ETHPSC is collected and stored in the...

The paper is available at: jsrad.org/wp-content/2015/Issue 12, 2015/13jj.pdf

Solar energy is a renewable energy heat source freely and widely available everywhere throughout the year. Heat pipes are very effective and passive heat transfer devices. A solar heat pipe collector performs well at high temperatures. Thermoelectricity could be utilized for power generation and provide cooling and heating. The combination of a sol...

The thermal performances of three water-filled thermosyphons subjected to evaporator wall temperatures between 30-150 o C were investigated. The effect of condenser cooling rates together with various fill ratios from 0.25-1.00, thermosyphon inclination angles from 23 o-90 o and aspect ratios from 5.0-10.0 were investigated. Power inputs from 5-405...

Condensed droplets in a two-phase closed thermosyphon (TPCT) are subject to two competing forces: contact line pinning force between the droplet and the wall of the TPCT and the body force due to gravity. By either reducing the contact line pinning force or increasing the body force can lead to significant enhancement in the heat transport capabili...

Heat pipe heat exchangers could be employed as run-around coils in air conditioning systems for enhanced dehumidification and cooling. This article reviews some of the works conducted on the cooling and dehumidification aspects in various air conditioning systems. They have been proved to be effective in enhancing dehumidification and reducing air...

Axial wall temperature distribution of R410a and water filled thermosyphons at various fill ratios and inclination angles are experimentally determined. Power was supplied using resistance band heaters. A water cooled jacket surrounded the condenser section. Power input ranged from 100 – 830 W. Fill ratios of 0.93, 0.66, 0.4 and 0.25 were employed...

System performance of a natural convection (thermosyphon) solar water heater depends on design and setup of collector and storage tank as well as environmental factors such as solar intensity, ambient temperature and wind conditions. The relative height separating the tank and collector mainly influences the magnitude of the thermosyphon flow rates...

The simultaneous heating and cooling ability of thermoelectric modules has neither been researched widely nor commonly exploited either in an industrial or domestic level. This paper presents the preliminary experiments of a thermoelectric system for simultaneous heating and cooling. The objective of the study is to determine the performance of the...

A conventional natural convection flat plate solar collector needs to be placed at an incline to the horizontal and exposed to the sun in order for the solar hot water heater system to work. This arrangement is satisfactory where there is ample roof top space to locate the collector and storage tank. In a high-rise apartment, space is at a premium...

System performance of solar water heaters depend upon collector and storage tank design and sizing and weather conditions (solar radiation intensity and ambient temperature). Nocturnal reverse flow and tank insulation dictate the degree of overnight water temperature drop in the storage tank. A tropical country like Malaysia has widely fluctuating...

Performance testing of solar heating systems and solar collectors according to International Standard Test procedures require sophisticated and expensive elaborate set-ups. Outdoor collector testing is not feasible in countries with widely fluctuating solar radiation conditions. Indoor testing does not give its true performance when the equipment i...

High ambient temperatures coupled with high humidity lead to uncomfortable conditions that are non-conducive for human comfort and productivity. Heat transmission through the roof could be reduced by providing insulation in the attic under the roof or above the ceiling. A roof solar collector could provide both ventilation and cooling in the attic....

Experimental investigations were conducted to determine the thermal performances of the Trombe wall and roof solar collector for solar passive cooling. Outdoor tests were conducted. Both Trombe wall and roof solar collector were able to supply adequate fresh air for ventilation purposes but the amount of induced air was insufficient to provide adeq...

Experimental investigations were conducted to determine the thermal performances of the Trombe wall and roof solar collector for solar passive cooling. Outdoor tests were conducted. Both Trombe wall and roof solar collector were able to supply adequate fresh air for ventilation purposes but the amount of induced air was insufficient to provide adeq...

The solar roof collector is modelled as a two dimensional air gap with one heated wall. The Boussinesq approximation is used to model the density variation. Four different air gap heights were simulated, namely 0.07m, 0.014m, 0,21m and 0.28m for a 2m long solar roof collector. The tilt angle of the solar collector was also varied between 15° and 55...

To quantify the potential for performance improvement of a standalone photovoltaic (PV) system, a test facility has been installed. This paper describes this development of a prototype standalone PV system. Essentially this entire system involves the integration of a personal computer (PC), data acquisition (DAQ), a battery array and a solar array...

This paper presents a simple method to determine the optimum sizes of solar array and battery bank for standalone photovoltaic (SPV) systems under the given load by using energy balance concept. The energy efficiency models of system components and the long-term solar radiation data obtained from Malaysian Meteorological Services Department are ado...

Heat pipes are low cost and efficient heat exchange equipment. They are suitable for low temperature heat or cold recovery systems. The latter could be employed to cool incoming warm fresh air in air-conditioned ventilation systems. R-134a is an environmentally friendly refrigerant and has been generally accepted as a substitute for R-12 and R-22....

A simple mathematical model of a solar chimney is proposed. The physical model is similar to the Trombe wall. One side of the chimney is provided with a glass cover which with the other three solid walls of the chimney form a channel through which the heated air could rise and flow by natural convection. Openings provided at the bottom and top of t...

A mathematical model of a solar chimney was proposed in order to predict its performance under varying ambient and geometrical features. Steady state heat transfer equations were set up using a thermal resistance network and solved using matrix inversion. Existing correlations of heat transfer coefficients were utilised. Property values for the air...