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This paper analyses wind speed estimation for Weibull distribution using various methods. According to a previous study, the existing methods primarily target areas with moderate to high-velocity rates, and Malaysia is a tropical country with pleasant breezes all year. As a result, this research aims to devise the most efficient method of forecasting wind speeds in low-speed areas. The researcher compared existing methods such as the Moment of Method, Empirical Method, Graphical Method, Maximum Likelihood Method and the newly proposed Alternative Graphical method. The finding indicates that the novel proposed approach, the Alternative Graphical Method, is superior regarding Goodness of Fit, Kolmogorov Smirnov and Chi-Square. For Kolmogorov Smirnov, the Alternative Graphical Method is 3.4 % better than the second-best method. At the same time, the usage of Chi-Square is again at a top position, with a 61 % disparity between it and the second and third best places. However, the Alternative Graphical Method is in second place for Anderson Darling, but the forecast performance with a minimum difference of 0.3 %. These findings imply that the Alternative Graphical Method capable of making more precise predictions than current methods.

An H-rotor vertical axis wind turbine (VAWTs) can operate independently in any wind direction, making it aerodynamically efficient and suitable to harness wind energy in low wind speed areas. The aerodynamic efficiency of VAWTs is highly dependent on the blade geometry, especially the blade tip. Tip vortices produced at the blade tips can negatively affect the VAWT’s aerodynamic efficiency. Adding endplates to the blade tips can minimize the effects of tip vortices on VAWTs. In this paper, several endplate designs are used to evaluate the effectiveness in improving the power coefficient, Cp of a VAWT at three different tip speed ratios (TSRs) using three-dimensional computational fluid dynamics (3D CFD) simulation. The power coefficients of VAWTs with endplates are compared with the baseline model with the same geometrical parameters where the baseline VAWT model is based on the experimental model from the literature. Since the focus of this study is on the blade tip design, a simplified 3D VAWT model is used where the supporting shaft and arms of the VAWT are excluded to reduce the needed computational capacity. Among the various endplate designs used in this study, the semi-circular inward endplate (ED3) with a diameter equivalent to 1.2 blade chord length showed the best improvement in the Cp which is by 7.45%, and 5.79% for at the TSRs of 2.19 and 2.58, respectively. The pressure difference on both sides of the blade was also examined. The results revealed that the endplate can prevent the flow from bypassing the blade tip, hence, preventing the occurrence of tip vortices while improving the aerodynamic efficiency near the blade tip, ultimately, improving the overall Cp of a VAWT.

Desiccant is a hygroscopic substance generally used in the dryer and air-conditioning system as a drying agent. The function of desiccant is to remove moisture from the air to reduce the humidity of the surrounding air been conditioned. This paper presents several works on the performance of desiccant material in the drying and air-conditioning application. It puts focus on the various advantages and disadvantages of the use of desiccant as a drying agent. There are some advantages of using desiccant include consistent drying and low energy usage. However, there are several disadvantages of using desiccants which are low capacity for moisture absorption and pressure drop in solid desiccant. Solar drying applications have some advantages such as being comparatively cheaper than other methods and less risk of spoiling the product. On the contrary, drying applications have disadvantages include being lower in comparison to the original foodstuff and drying foods eventually leads to shrinkage. The advantages of using desiccant in air-conditioning applications offer dehumidified fresh air to keep the building's temperature in a comfortable range and enhances water recovery efficiency. There are disadvantages such as desiccant will substantially impact the system's performance and desiccant should be cooled after completely dried.

Renewable energy systems are technologies that can generate electricity from solar, wind, hydroelectric, biomass, and other renewable energy resources. This research project aims to find the best renewable energy technology combinations for several scenarios in Malaysia. The strategies are analysed by evaluating the investments in the renewable energy systems in each of the decided scenarios in Malaysia, Pekan, Pahang and Mersing, Johor, using HOMER Pro software. The finding shows that the PV–wind hybrid system has a better net present cost (NPC) than the other systems for both scenarios, which are USD −299,762.16 for Scenario 1 and USD −642,247.46 for Scenario 2. The PV–wind hybrid system has 4.86-year and 2.98-year payback periods in Scenarios 1 and 2. A combination of RE technologies yielded fewer emissions than one kind alone. The PV–wind hybrid system provides a quicker payback period, higher money savings, and reduced pollutants. The sensitivity results show that resource availability and capital cost impact NPC and system emissions. This finding reveals that integrated solar and wind technologies can improve the economic performance (e.g., NPC, payback period, present worth) and environmental performance (e.g., carbon dioxide emissions) of a renewable energy system.

In this study, flow and heat transfer characteristics of binary hybrid nanofluid (CuO / MgO-water) through new configuration channel, namely: the curved-corrugated channel, are evaluated numerically using the multi-phase mixture model. The binary hybrid nanofluid is experimentally prepared with average diameters of 40 nm and three volume fractions of nanoparticles of 1%,3%, and 5%. Measured thermophysical properties are employed to simulate the complex flow within the tested configurations of channel with presence of E-shaped baffles. Various geometric parameters such as gap ratio (GR = 0.2,0.3,0.4, and 0.5), blockage ratio (BR = 0.2,0.25,0.3, and 0.35), and pitch angle (β = 10°, 12.5°, and 15°) at different Reynolds number (8000–28,000) and volume fraction (φ) of CuO / MgO particles (0–5%) are considered to serve the purpose. The findings uncover that the binary hybrid nanofluid improves the thermophysical properties of the base fluid and thereby boost the thermal performance of the system. It is found that the thermal-hydraulic performance (THPF) of binary hybrid nanofluid enhances with increasing volume fraction, and this enhancement is close to 38% when Re = 28,000 and φ = 0.05. Regards the geometric parameters, THPF enhances by increasing the blockage ratio and decreasing the pitch angle while recording the best improvement at the particular gap ratio, i.e. 0.3.

Among renewable energy resources, wind energy is one of the best alternative for power generation. Recently, vertical axis wind turbine (VAWT) received renewed interest as small-scale wind energy converter due to its suitability for urban application, where the wind condition is known to be unsteady and turbulence. Amongst various type of VAWTs, H-type Darrieus rotor has become more popular, thanks to its simple construction features, resulting to low manufacturing and installation cost. The aim of this paper is to evaluate numerically the power performance of straight-bladed Darrieus VAWT with different turbine solidity using computational fluid dynamic (CFD) technology. A series of two-dimensional CFD simulations of a three-bladed H-type Darrieus rotor were performed with 3 different solidities, σ (0.3, 0.5 and 0.7) to evaluate their power performance. Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations were used to calculate the instantaneous moment coefficient, Cm and power coefficient, Cp over a range of tip speed ratio, λ (0.5–4.5) with a free stream velocity of 8.0 m/s. The simulation results show that high solidity turbine performed well at low values of λ while turbine with low solidity has a wider operating range of λ and performed better at λ > 3.0 due to less blade-wake interactions between upstream and downstream halves of the turbine and lower blockage effect. The findings lend substantially to our understanding of physics flow around blades and turbine in order to optimize the power performance of small scale straight-bladed Darrieus VAWT operating in unsteady and turbulence wind condition.

Wind energy has historically helped many people and has been utilized for farming and seafaring. Today, modern usage is more comprehensive such as generating electricity. However, its usage in Malaysia remains at an all-time low. Numerous factors contribute to this result. Consequently, a full assessment of wind energy in a particular region is deemed necessary. This study investigates wind speed distribution in Mersing. It also illustrates the period during which the regional distribution statistics changed. The researcher used Autofit 5.6 and the Maximum Likelihood Method to figure out the parameter value of each distribution for wind speed data from 2012 to 2016. This study utilized three distinct methods of Goodness of fit (GOF) to estimate the optimal distribution ranking, such as Chi-Square, Anderson-Darling, and Kolmogorov-Smirnov. The results reveal that the Burr, Gamma, and Lognormal distributions correlate to the wind speed data in Mersing and the Burr distribution is the most appropriate. In addition, the findings indicate that distribution changes occur at a minimum rate of 8.89%. In conclusion, these findings reveal that there has been no significant change over the five years. This information enables stakeholders to determine whether they will earn a profit owing to changes in the distribution of a particular area, reducing risk.

Passive flow control devices have been proposed by many researchers for suppressing dynamic stall and enhancing the aerodynamic performance of turbomachinery including wind turbines. These technologies are usually cheap, easier to implement, and no additional energy needed. In the present study, the effects of adding trailing edge wedge tail (WT)on the aerodynamic characteristics of a static airfoil have been evaluated. The aerodynamic behavior of 2D-NACA0021 airfoil equipped with WT have been studied numerically using the commercial code ANSYS FLUENT to solve the Reynolds-Averaged Navier–Stokes equation (RANS). The effect of varying heights and lengths to height ratios (L/H) of WT have been studied. The results showed that the aerodynamic efficiency of NACA0021 airfoil influenced significantly by height of WTs comparing to slightly influence by length at L/H

The increase in module operating temperature above 25 °C can be detrimental to the electrical output performance of photovoltaic (PV) modules. The study introduces a novel truncated multi-level fin heat sink (MLFHS) subject to natural convection for photovoltaic (PV) cooling. The proposed fin geometry aims to improve the heat transfer by inducing abrupt change within the boundary layer in the fin confined region through the multi-level fin height. The effect of fin spacing, fin height, and fin thickness on the heat transfer properties of the MLFHS was investigated numerically using finite element analysis (FEA). The parametric study was conducted to compare the thermal performance of the MLFHS with the conventional rectangular plate-fin heat sinks by varying the fin spacing (p = 10–35 mm), fin height (h = 60–120 mm), and fin thickness (t = 0.5–1.5 mm). The results indicate that the average temperature decreases first and increases with fin height, fin spacing, and fin thickness. The findings were promising with an optimized fin heat sink showing a decrease in the average PV module temperature as high as 6.13% and improved power output by 2.87%. The proposed fin geometry provides a promising heat transfer approach for PV cooling applications.

Wind turbines in the context of integration in an urban environment are considered as one of the most promising technologies for the efficient diffusion of renewable energy sources. However, situations such as low wind velocity, highly turbulent and skewed wind flow conditions are commonly encountered in this environment. This misaligned flow could affect the horizontal axis wind turbine performance. The vertical axis wind turbine (VAWT) is more suitable to operate under these unfavorable conditions. Nevertheless, the conventional VAWT has low efficiency and poor self-starting characteristics. Therefore, a novel design of deflector integrated cross axis wind turbine (CAWT) is proposed. Tests were carried out to harness wind energy from both the horizontal and vertical components of the skewed flow induced by the deflectors. A semi-empirical approach was also developed to analyse the performance of the CAWT. The aerodynamic behaviour of the CAWT was determined by combining the blade element momentum (BEM) model and double multiple streamtube theory (DMST). The approach showed notable agreement between the experimental and theoretical results (9.8%–14.2% difference). In conclusion, the findings from the experiment and the model showed that the concept has very good potential in the renewable energy industry.

In this paper, a performance analysis of a photovoltaic (PV) tracking system is conducted, to evaluate its performance based on field data measurement. A dual-axis tracker with smart algorithms called maximum light detection (MLD) applied in the solar energy generation system is analyzed. In a tropical country that having a massive cloud cover throughout the year, the sky condition is categorized as sunny, intermittent and gloomy. The comparative results show that the system with MLD tracker improved the energy generation significantly all sky conditions.

This paper presents an experimental study comprising two CMA solar collectors with parallel and series arrangements on a forced convection solar drying system. The parallel and series solar collectors were investigated to evaluate the arrangement type's effect on the thermal performance. The experiments were conducted using artificial solar radiation that varies from 300 to 900W/m2 with the air velocity of 0.5–2 m/s. The arrangement's efficiency was evaluated based on the drying chamber's thermal delivery from the collectors, thermal gains, and drying efficiencies, including air velocity effect and pressure drop. Results show that the solar collectors' parallel arrangement leads to higher air temperature inside the drying chamber than the series by 3.87 °C. The thermal efficiency of 33.89% is achieved for the parallel setup than the series of 27.73%. The series arrangement is superior to the parallel in terms of the pressure drop across the solar drying system. Drying efficiency is observed at a higher air velocity of 2 m/s for both arrangements than lower airflow of 0.5 and 1 m/s. Parallel configuration showed promising performance in drying efficiency and low energy usage compared to the series arrangement in which the negative impact of higher pressure-drop was compensated.

The electrical output performance of photovoltaic (PV) modules are sensitive to temperature variations and the intensity of solar irradiance under prolonged exposure. Only 20% of solar irradiance is converted into useful electricity, and the remaining are dissipated as heat which in turns increases the module operating temperature. The increase in module operating temperature has an adverse impact on the open-circuit voltage (Voc), which results in the power conversion efficiency reduction and irreversible cell degradation rate. Hence, proper cooling methods are essential to maintain the module operating temperature within the standard test conditions (STC). This paper presents an overview of passive cooling methods for its feasibility and economic viability in comparison with active cooling. Three different passive cooling approaches are considered, namely phase change material (PCM), fin heat sink, and radiative cooling covering the discussions on the achieved cooling efficiency. The understanding of the above-mentioned state-of-the-art cooling technologies is vital for further modifications of existing PV modules to improve the efficiency of electrical output.

This study aims to experimentally investigate the passive cooling performance of a concentrated PV module, using two different designs of novel passive fin heat sinks namely, lapping and longitudinal. Design of Experiment (DOE) approach technique was employed to identify the optimum design parameters in terms of fin height, fin pitch, fin thickness, number of fins and tilt angle. The experimental work was carried out under real environmental conditions at optimum design parameters of the passive fin heat sinks. At average solar irradiance of 1000 W/m2 and ambient temperature of 33 °C, results showed that, passive cooling with lapping fins demonstrate the best performance with mean PV module temperature 24.6 °C lower than the reference PV module, and hence, the achieved electrical efficiency and power output are as high as 10.68% and 37.1 W, respectively. Finally, Life Cycle Cost Analysis (LCCA) was conducted. The analysis showed that the payback period for PV module with longitudinal, lapping fins and bare PV module are 4.2, 5 and 8.4 years respectively. Therefore, PV module cooling using passive technique particularly with lapping fins design is concluded as the preferred option.

Energy is the main driving force of an economy. Due to which many advancements in renewable energy technology have been witnessed over the decade. However, not all countries have efforts in the same direction and have continued using coal-based technology. These old technologies have a sizable energy wastage in the form of fuel thermal energy (Kinetic Energy). The said wastage can be harnessed by using a specifically designed recovery turbine deployed in the industrial stack. Keeping in mind the same, this research focuses on a mathematical model to develop the best-suited design for the utmost augmentation of the kinetic energy. A Convergent-Divergent nozzle with varying ratios of entry to the throat area (Aent/A*) and exit to the throat area (Ae/A*) were subjected to mathematical formulations. The combinations of Aent/A* and Ae/A* tested were (a)1.489 and 1.256 (b) 1.78 and 1.97 respectively. The results indicate that the combination “b” is a better option owing to the largest velocity augmentation. The maximum velocity at the throat was noted at 3.9 times the inlet velocity, which would result in a larger power output by the turbine positioned there. Post analysis of the Mach number (Ma), it was also concluded that the flow is incompressible, and no shockwaves were seen. The development of such a novel technology would result not only in financial saving for the industries but also reducing the environmental impact due to non-renewable sources of energy.

Malaysia demonstrates its commitment to alleviating the negative climate and energy issues through various initiatives. One of the latest initiatives is the amendment of the net-energy metering (NEM) scheme that takes effect from 2019. This paper presents the distribution of energy to the residential house that has a grid-connected solar photovoltaic (PV) system installed. The study quantifies the percentage of energy consumed from the PV system and the grid as well as the percentage of PV generated energy that is exported to the grid. On average, 38% of generated energy was used for self-consumption that contributed to 28% of the total consumption. Economic evaluation over a 25-year lifecycle of the PV system is also conducted shows that the simple payback period for NEM 2019 and NEM 2016 is 8 years and 20 years, respectively. The latest version of NEM shows a superior advantage compared to the previous one which may attract more investments in PV generation.

This study aims to combine planar reflector and backplate extended surface to the PV module to optimize its efficiency. A parametric study based on lapping fin height, number fins, fin spacing, windspeed and solar irradiance on the PV module performance were investigated using CFD, ANSYS, FLUENT. 3-D, Navier–Stokes energy equations were solved using ANSYS, FLUENT to perform numerical computations. Meanwhile, the bare PV module temperature has been calculated using Engineering Equation Solver (EES) software. The results revealed that as the fin pitch increases from 20 to 60 mm this leads to decrease number of fins from 20 to 10 fins which at the same time increased the PV module temperature from 44.13-54.01 °C. The PV module temperature without cooling was reached 64.3 °C; meanwhile with 18 lapping fins and 27.7 mm fin pitch the PV module temperature reduced to 39.73 °C which improved the electrical efficiency to 11.2% when compared to bare PV 9.81% with a temperature difference 24.57 °C at 1000 W/m2. Finally, we conclude that the lapping fins have a superior performance in reducing PV module temperature. Furthermore, it was found that the aluminum thickness of the designed fins above 2 mm showed a negligible effect on the PV power and efficiency. Keywords: Passive cooling, Efficiency enhancement, Experimental investigation, Computational fluid dynamics (CFD), EES

Natural ventilation, which is a common method used in tropical climate countries, can provide a high rate of airflow to maintain good indoor air quality and thermal comfort. However, the use of natural ventilation alone as passive cooling strategy is insufficient to improve indoor thermal environment. Thus, this study aims to determine the existing thermal comfort conditions in a naturally ventilated public hospital ward by using three methods: simulation works, objective measurements and field surveys. The combination of all these methods in measuring thermal comfort is essential in acquiring the most accurate results and has yet to be implemented in any public hospital in the tropics on the basis of the literature review conducted. The simulation results presented that more than half of the total occupants in the ward feel discomfort, with a predicted mean vote (PMV) between 1.0 and 1.6 and a predicted percentage of dissatisfied between 40% and 56%. On-site measurements recorded the same PMV reading, indicating slightly warm and warm, on the basis of the ASHRAE Standard 55 assessment scale. By contrast, the results of the survey questionnaire showed a different perception of the occupants, with 82% of the respondents voting in the range of warm to hot scale. The thermal conditions in the naturally ventilated ward studied for two months in 2020 were found to be uncomfortable and required further improvement. Knowledge of the climatic characteristics and the current state of the indoor thermal environment will help the building owners strategise an appropriate bioclimatic design approach.

Hospital buildings are the main energy users among government facilities which require substantial energy reduction to save its annual operational costs . At the same time, the Ministry of Health Malaysia has set a policy for all hospitals to achieve green building certification, which in line with its global commitment to conserve the environment. Energy efficiency is an important component in every green building rating tool because of its high potential on point scoring. Thus, there is a need to find the most appropriate method to explore energy saving opportunities as much as possible. The overall aim of this article is to evaluate the potential for energy saving in public hospital using a systematic approach. Three methods are applied in this approach which involved energy audit, empirical evidence and simulation works. Energy audit predicts that the chiller system provides the highest energy saving amount of 1,535,175.40 kWh/year (45.54 %) with discounted payback period of 7.15 years. A chiller retrofit measure was implemented as pilot project and the predicted energy savings were validated by empirical evidence. The actual energy saving of 1,688,347.02 kWh/year (50.08 %) was obtained from the chiller system retrofit and slightly higher than what was predicted with discounted payback period of 6.29 years. Apart from active measures, many more energy saving potentials can still be explored through passive strategies. Simulation method is used to establish energy baseline as the basis for predicting energy saving potential for passive strategies that cannot not be measured through energy audit. The combination of these methods is essential to optimize the potential of energy saving through active and passive strategies that have so far has never been implemented in any public hospital in Malaysia.

The novel exhaust air energy recovery turbine generator is designed to recover part of energy from a fan-powered exhaust air system which represented by a cooling tower. The discharge wind from the cooling tower varies throughout the radius makes it a non-uniform profile. A vertical axis wind turbine (VAWT) is placed at the outlet of a cooling tower to recover the energy. The VAWT behavior in the non-uniform wind stream from the exhaust air system is studied by experiment and double multiple stream tube (DMST) theory. A novel application of the DMST model is applied for non-uniform wind stream. The experimental results show that best horizontal position of the VAWT is at a distance of about 2/3 of the outlet radius with respect to turbine rotation. Theoretical analysis explains the wind turbine behavior in the non-uniform wind stream as acquired from the experiment. For the selected wind turbine, it is the best to match the highest wind velocity region to the wind turbine at the range of 45° to 115° azimuth angle. This innovative system has a huge potential due to wide application of exhaust air system globally.

An ongoing project to implement a mini standalone solar photovoltaic (PV) generation system of 2.5 kWp capacity at the eco-tourism centre of Liogu Ku Silou-Silou (EPLISSI), Sabah, was initiated in 2019. Since the solar panel support (ground mounting) used in this project will be erected separately, the main goals of this study are to estimate the optimum tilt angle, βopt, and orientation for the solar PV modules. To achieve these goals, the Liu and Jordan isotropic diffuse radiation model was used (1960). Another three isotropic diffuse sky radiation models (Koronakis model, Badescu model, and Tian model) were applied to estimate the optimum tilt angle with the orientation kept facing due south. For verification purposes, the PV power output data obtained from an online PV simulator known as Global Solar Atlas or GSA 2.3 was used and compared to the results of the four isotropic models. The results suggest that the Tian model is more suitable for approximating insolation, as it was proven to have the lowest difference among all models and is in close agreement with the result of the optimum tilt angle provided by GSA 2.3. However, the outcomes demonstrated from the isotropic models propose an error up to 30% (in the range of 31% to 32%) as compared to GSA 2.3.

The tropical climate with its high average temperatures throughout the year affects the thermal comfort of buildings, especially for naturally ventilated spaces. The government’s move to turn hospitals into green buildings is seen in line with the global commitment to conserve the environment and the country’s current policy of supporting sustainable development. To achieve this goal, energy efficiency and thermal comfort need to be given priority in the focus on hospital planning and implementation for a better quality of the indoor environment. This literature review has led to the need to improve thermal comfort in natural ventilated wards in government hospitals. Some wards are built without air conditioning to save on construction costs, reduce utility costs through low energy consumption, as well as the need for infection control and airborne infections. However, current climate change requires a special study of thermal comfort in wards that use natural ventilation. An innovative solution is proposed to solve the problem statement identified in the reviewed literature through the application of solar PV/T systems and heat pumps. This hybrid system re-uses the heat energy (cogeneration) generated from solar PV panels to be cooled by heat pumps and is then pumped into the ward for cooling purposes. The proposed system has the potential to improve thermal comfort in natural ventilation wards and increase efficiency of the solar PV system for optimal electricity generation as well as improve the overall energy performance of buildings through low-energy cooling systems. It is not only solving the thermal comfort issue but also avoid the use of extra energy for cooling by optimizing the renewable energy.

This paper aims to investigate the exergetic sustainability index (SI) of a dual-fluid PV/T type solar collector that integrates both air and water into the same solar collector. The contribution of the exergy efficiency of each of the dual fluid PV/T collector's components to the overall sustainability of the whole system was analysed. A theoretical approach based on an experimentally validated numerical model was employed. The results show that the SI of the PV component of the dual fluid PV/T system is in general higher than the solar thermal component by approximately 9% since it is higher in quality. When evaluated under three different climatic conditions, the contribution of the thermal component as a cooling medium to the PV is only prominent in hot climates with SI higher by 4% compared to the stand-alone PV system. For the cool and cold temperate climates, the difference is less than 0.1%.

This paper studies the optimization of an innovative exhaust air recovery wind turbine generator through computational fluid dynamic (CFD) simulations. The optimization strategy aims to optimize the overall system energy generation and simultaneously guarantee that it does not violate the cooling tower performance in terms of decreasing airflow intake and increasing fan motor power consumption. The wind turbine rotor position, modifying diffuser plates, and introducing separator plates to the design are considered as the variable factors for the optimization. The generated power coefficient is selected as optimization objective. Unlike most of previous optimizations in field of wind turbines, in this study, response surface methodology (RSM) as a method of analytical procedures optimization has been utilised by using multivariate statistic techniques. A comprehensive study on CFD parameters including the mesh resolution, the turbulence model and transient time step values is presented. The system is simulated using SST K-ω turbulence model and then both computational and optimization results are validated by experimental data obtained in laboratory. Results show that the optimization strategy can improve the wind turbine generated power by 48.6% compared to baseline design. Meanwhile, it is able to enhance the fan intake airflow rate and decrease fan motor power consumption. The obtained optimization equations are also validated by both CFD and experimental results and a negligible deviation in range of 6–8.5% is observed.