Hybrid techniques to enhance solar thermal: the way forward

Solar is one of the pillars for clean and environment friendly energy. The drawback of the solar is the interruption during the night and cloudy and rainy weather. This paper presents the author’s experience on enhancing the solar thermal systems by integration techniques with either other energy resources or thermal energy storages (TES). The present works includes the hybrid solar drying through integration with thermal backup unit. The experimental results on hybrid drying showed enhancement of 64.1% for Empty Fruit Bunch, and 61.1% for chili pepper, compared with open solar mode drying. Secondly, solar water heating was proved to be sufficient to supply hot water during the day and night time by integration with TES. The experimented system was able to maintain the water hot up to the next morning. On large scale and industrial application, experimental results on modified inclined solar chimney had shown enhancement via integration with wasted flue gas. By this technique, the system was developed to operate 24 hours a day. The efficiency was enhanced by 100% in case of hybrid operation compared with solar mode operation. The research results are demonstrating that the integration techniques can contribute effectively in enhancing the performance of the thermal solar systems.The author acknowledges Universiti Teknologi PETRONAS for providing the financial, technical and logistic support to execute the solar hybrid program. The program is sponsored under many internal research funds, e.g. STIRF no. 24/07.08, STIRF no. 44/08.09, URIF 19/2012 and URIF 22/2013. Ministry of Higher Education of Malaysia is acknowledged for providing the research fund of the solar hybrid drying program under PRGS scheme

The transverse shear deformation behaviour of magneto-electro-elastic shell

Compared to the large number of possible magneto-electro-elastic shell theories, very few exact solutions determining the in-plane stresses, electric displacements and magnetic inductions are possible. While, solving the magneto-electro-elastic shell equations in terms of thermo-magneto-electro-elastic generalized field functions on arbitrary domains and for general conditions exactly are not always possible. In the present work, a linear version of magneto-electro-elastic shell with simply supported boundary conditions, solved exactly, provided that the lamination scheme is cross-ply or anti-symmetric angle-ply laminates. The exact solution that introduced herein can measure the in-plane stresses, electric displacements and magnetic inductions. It also allow for an accurate and usually elegant and conclusive investigation of the various sensations in a shell structure. However, it is important for micro-electro-mechanical shell applications to have an approach available that gives the transverse shear deformation Behaviourfor cases that cannot examine experimentally. An investigated examples were accompanied and noteworthy conclusions were drawn which highlight the issues of the implementation of the exact solution, implication of the effects of the material properties, lay-ups of the constituent layers, and shell parameters on the static Behaviour

Overview of Hazardous Waste Management Status in Malaysia

This chapter reviews the status of hazardous waste management in Malaysia. It highlights the sources of the hazardous waste, government policies on waste generation and management, the involvement of the stakeholders, and the various management procedures adopted in Malaysia. Currently, the manufacturing sector is the major contributor in hazardous waste generated in Malaysia. Other sectors that contribute include household, agriculture, medical, and other industrial sectors. Malaysian government’s resolve on human health protection and safeguarding the environment prompted various acts, regulations, and orders such as the popular Environmental Quality Act (EQA) 1974. The regulations made pursuant to the Environmental Quality Act have continuously improved to address the issues on the definition and classifications of hazardous waste and the management process in Malaysia. The management of hazardous waste in Malaysia is effectively growing as a result of continuous review of the regulations and enforcement of the acts. The stakeholders in the industries have also been active in keeping to the EQA regulations to keep the environment safe as much as possible

Applications of Compound Nanotechnology and Twisted Inserts for Enhanced Heat Transfer

Nanoadditives are a type of heat transfer enhancement techniques adopted in heat exchangers to improve the performance of industrial plants through improvement of the thermal properties of base fluids. Recently, various types of inserts with nanofluids are adopted to enhance the thermal performance of double pipe heat exchangers. In the current article, TiO2/water nanofluid with multiple twisted tape inserts was investigated as a hybrid enhancement technique of heat transfer in straight pipes. The investigations were carried out experimentally and numerically at Reynolds numbers varied from 5000 to 20,000. Using nanofluid with 0.1% TiO2 nanoparticles volume fraction demonstrated enhanced heat transfer with slight increase in pressure drop. Results are showing a maximum increase of 110.8% in Nusselt number in a tube fitted with quintuple twisted tape inserts with 25.2% increase in the pressure drop. However, as the article is representing a part of specified book on heat exchangers, the literature has been extended to provide sufficient background to the reader on the use of nanotech, twisted inserts, and hybrid of compound nanofluids and inserts to enhance heat transfer processes

A NOVEL CELL BY CELL ARTIFICIAL NEURAL NETWORKS APPROACH FOR PREDICTING THE TEMPERATURE OF STEADY STATE, INCOMPRESSIBLE, LAMINAR FLOWS

A cell-by-cell artificial neural network approach is used to predict the temperature field of steady-state, incompressible, laminar flows in a two-dimensional computational domain. The temperature field is characterized by the initial flow velocity, fluid temperature and the temperature of the wall boundaries. Two types of neural network architectures are developed in this research, namely cascade-forward and feedforward models. Both models are trained using Levenberg-Marquardt and Bayesian regularization backpropagation algorithms. The training data for the models are obtained by solving the Navier-Stokes equations for steady-state, incompressible, heat conducting laminar flow in two-dimensional domain using commercial ANSYS Fluent software. The results show that the predicted values produced by the ANN models are in good agreement with the CFD simulation data. Even though the introduction of artificial neural networks at the cell level increases the complexity of the training process, this drawback is compensated by the increase in flexibility (generality) of the models. More importantly, the results show that the cell-by-cell artificial neural network approach is capable of providing an accurate prediction of the temperature field for the fluid flow investigated in this research, as indicated by the statistical indices used to evaluate the performance of prediction models. The feedforward ANN model trained using the Bayesian regularization backpropagation algorithm gives the most accurate predictions among all models

Three Dimensional Simulation of Supersonic Flow over Missiles of Different Shapes

In this work, a three-dimensional primitive variable of supersonic flow over missiles was computed based on finite difference computational fluid dynamic methods. The problem was considered is to deal with external, inviscid, compressible supersonic- flow over three-dimensional missiles with and without canard. Euler equations were solved using time-marching MacCormack’s explicit technique. The flow conditions are taken at sea level and Mach number was tested up to 4.0. To deal with complex shape of missiles the so-called “body fitted coordinate system” was considered and the algebraic and elliptic methods were used to generate grids over missiles. The number of iterations and the number of mesh points depending on Mach number. The result indicate, that for the same Mach number, the increasing of mesh points, lead to increase of the number of iteration

EXPERIMENTAL INVESTIGATION OF SOLAR VORTEX POWER GENERATION SYSTEM INTEGRATED WITH SENSIBLE THERMAL ENERGY STORAGE

Solar updraft power technologies suffer low efficiency and require a large collection area. Enhancement techniques are essential to overcome these setbacks. This paper investigates and discusses the effect of extended Sensible Thermal Energy Storage (STES) outside the canopy of the Solar Vortex Power Generation (SVPG) system. The extended sensible thermal energy storage integration is evaluated experimentally utilizing an SVPG model installed in the solar research site in Universiti Teknologi PETRONAS. The system consists of an (8-m-Dia). solar collector and a vortex generator. The selected material of the STES is black-painted pebbles that covered the ground underneath the canopy of the solar collector and then extended by 1 m outside the canopy. The variables considered for the performance evaluation are ambient, air inlet and outlet of the collector temperatures, incident solar irradiance, and air outlet velocity. Two cases have been studied, one with black painted pebbles covering the ground up to the outer diameter of the canopy (8-m-Dia) and the second is 1.0 m extended coverage outside the canopy (10-m-Dia). The performance of the SVPG is proven to enhance by the extension of the STES beyond the collector area. The extension of STES increased the mean thermal efficiency value by 0.85% and increased the mass flow rate by 0.01 kg/s. The performance indicator is increased by around 19.3%. It could be concluded that the extension of pebbles outside the canopy increases the amount of solar photothermic conversion, leading to improved efficiency of the SVPG system

Evaluation of 15-m-Height Solar Chimney Model Integrated with TES under Tropical Climate

Received: 11 October 2023. Revised: 3 November 2023. Accepted: 1 December 2023. Available online: 29 December 2023.The present study examines a solar chimney power generation model under tropical conditions, with a focus on the impact of ground absorber dimensions on system efficacy. An experimental and numerical analysis was conducted using a 15-meter-high solar chimney, where the ground was transformed into a sensible thermal energy storage system through the application of black-painted pebbles. Three configurations were assessed to determine system performance: Case-1 and Case-2, featuring collector diameters of 4.9 m and 6.6 m respectively, and Case-3, which introduces an innovative design extending the diameter of the sensible thermal energy storage (TES) by 2.0 m beyond the collector's canopy. Performance was gauged using a metric defined by the product of mass flow rate and temperature increase of the air. Numerical models were validated against experimental outcomes, with results showing a satisfactory correlation. It was found that the performance metric in Case-2 doubled, while in Case-3, it tripled relative to Case-1. The enhancement in performance in Case-3 was further evidenced by a 30.4% increase in air velocity at the chimney base over Case-2, and a 36.7% increase over Case-1, highlighting the efficacy of the extended sensible TES. These findings suggest that enlarging the TES area beyond the collector's canopy can significantly improve solar chimney performance, potentially enabling a reduction in construction scale and a concurrent decrease in electricity production costs. This approach represents a promising avenue for addressing the dual challenges of structural height and efficiency that currently hamper the feasibility of solar chimney power generation on an industrial scale.The authors acknowledge Universiti Teknologi PETRONAS for the support in conducting the research and producing this paper using the facilities in the solar research site

Potential of Renewable Energy Resources with an Emphasis on Solar Power in Iraq: An Outlook

This study presents an outlook on the renewable energies in Iraq, and the potential for deploying concentrated solar power technologies to support power generation in Iraq. Solar energy has not been sufficiently utilized at present in Iraq. However, this energy source can play an important role in energy production in Iraq, as the global solar radiation ranging from 2000 kWh/m2 to a 2500 kWh/m2 annual daily average. In addition, the study presents the limited current solar energy activities in Iraq. The attempts of the Iraqi government to utilize solar energy are also presented. Two approaches for utilizing concentrated solar power have been proposed, to support existing thermal power generation, with the possibility of being implemented as standalone plants or being integrated with thermal power plants. However, the cost analysis has shown that for 50 kW concentrated solar power in Iraq, the cost is around 0.23 US cent/kWh without integration with energy storage. Additionally, notable obstacles and barriers bounding the utilization of solar energy are also discussed. Finally, this study proposes initiatives that can be adopted by the Iraqi government to support the use of renewable energy resources in general, and solar energy in particular

RIBBED DOUBLE PIPE HEAT EXCHANGER: ANALYTICAL ANALYSIS

This paper presents the findings obtained by modeling a Double Pipe Heat Exchanger (DPHE) equipped with repeated ribs from the inside for artificial roughing. An analytical procedure was developed to analyze the thermal and hydraulic performance of the DPHE with and without ribbing. The procedure was verified by comparing with experimental reported results and they are in good agreement. Several parameters were investigated in this study including the effect of ribs pitch to height ratios, P/e= 5, 10, 15, and 20, and ribs to hydraulic diameter ratios, e/Dh= 0.0595, 0.0765, and 0.107. These parameters were studied at various operating Reynolds number ranging from 2500 to 150000. Different installation configurations were investigated, too. An enhan-cement of 4 times in the heat transfer in terms of Stanton number was achieved at the expense of 38 times increase of pressure drop across the flow in terms of friction facto values