Modeling magnetic nanopolymer flow with induction and nanoparticle solid volume fraction effects : solar magnetic nanopolymer fabrication simulation

A mathematical model is presented for the nonlinear steady, forced convection, hydromagnetic flow of electro-conductive magnetic nano-polymer with magnetic induction effects included. The transformed two-parameter, non-dimensional governing partial differential equations for mass, momentum, magnetic induction and heat conservation are solved with the local non-similarity method (LNM) subject to appropriate boundary conditions. Keller’s implicit finite difference “box” method (KBM) is used to validate solutions. Computations for four different nanoparticles and three different base fluids are included. Silver nanoparticles in combination with various base fluids enhance temperatures and induced magnetic field and accelerate the flow. An elevation in magnetic body force number decelerates the flow whereas an increase in magnetic Prandtl number elevates the magnetic induction. Furthermore, increasing nanoparticle solid volume fraction is found to substantially boost temperatures. Applications of the study arise in advanced magnetic solar nano-materials (fluids) processing technologies

Passive power generation and heat recovery from waste heat

This research presents a passive method of waste heat recovery and conversion to electricity using Thermo-Electric Generator (TEG). For this purpose, a lab scale bench-top prototype of waste heat recovery and conversion system was designed and fabricated. This bench top system consists of the thermoelectric generators (TEGs) sandwiched between two heat pipes, one connected to the hot side of the TEG and the second connected to the cold side of the TEG. A 2 kW electric heater was used to replicate the waste heat. An electric fan was used to provide air into the system. A theoretical model was developed to predict the system performance. The model was found in good agreement with the experimental data

Feasibility of electrical power generation using thermoelectric modules via solar pond heat extraction

Solar pond undoubtedly has been a reliable source of low grade heat supply by acting as both collector and storage for the incoming solar radiation. The thermal efficiency of the solar ponds is between 15 and 25% of the incoming horizontal solar radiation. Meanwhile, the thermoelectric technology enables the conversion of heat into electricity using thermoelectric modules. In this paper, the feasibility of the system by combining solar pond and thermoelectric modules is presented. This system can be achieved by using a thermoelectric modules-embedded heat exchanger module that will able to extract the heat available from the lower convective zone of the solar pond. The analysis in this paper was conducted by investigating the solar ponds operating in different climate conditions, which are Group A (Kuala Lumpur), Group B (Riyadh) and Group C (Melbourne and Granada) base on Köppen climate classification. The theoretical feasibility draws the limit on the performance and cost of the solar pond-thermoelectric system under commercially available thermoelectric technology at the present state. Later, the result was contrasted against the performance of the power generation units operate under realisable operating condition with solar pond. The result in this study revealed that, under ideal condition, the system is at least 10 times costly compared to other renewable energy sources like off-grid solar photovoltaic system with storage. Meanwhile, at its best operating climate, this system will be able to achieve annual carbon dioxide reduction of 2.38 kg/m2-year in a practical case

Simultaneous power generation and heat recovery using a heat pipe assisted thermoelectric generator system

This research explores a new method of recovering waste heat and electricity using a combination of heat pipes and thermoelectric generators (HP-TEG). The HP-TEG system consists of Bismuth Telluride (Bi2Te3) based thermoelectric generators (TEGs), which are sandwiched between two finned heat pipes to achieve a temperature gradient across the TEG for thermoelectricity generation. A theoretical model was developed to predict the waste heat recovery and electricity conversion performances of the HP-TEG system under different parametric conditions. The modelling results show that the HP-TEG system has the capability of recovering 1.345 kW of waste heat and generating 10.39 W of electrical power using 8 installed TEGs. An experimental test bench for the HP-TEG system is under development and will be discussed in this paper

Experimental investigation on effect of adhesives on thermoelectric generator performance

Thermoelectric generators (TEGs) convert heat energy into electricity. Currently, these devices are attached to heat exchangers by means of mechanical devices such as clamps or fixtures with nuts and bolts. These mechanical devices are not suitable for use in harsh environments due to problems with rusting and maintenance. To eliminate the need for such mechanical devices, various kinds of adhesives used to attach thermoelectric generators to heat exchangers are investigated experimentally in this work. These adhesives have been selected based on their thermal properties and also their stability to work in harsh environments to avoid damage to the integrity of the attachment over long periods of time. Stainless-steel plates were attached to a thermoelectric generator using the adhesives. The introduction of the adhesive as a means of attachment for thermoelectric generators contributes to increase the thermal resistance to heat transfer across the TEG. The adhesive layers increased the thermal resistance of the thermoelectric generator by 16% to 109%. This work examines the effect of the adhesives on the thermal performance and power output of a single thermoelectric generator for various heat inputs

Experimental analysis of thermoelectric heat exchanger for power generation from salinity gradient solar pond using low-grade heat

Salinity gradient solar ponds act as an integrated thermal solar energy collector and storage system. The temperature difference between the upper convective zone and the lower convective zone of a salinity gradient solar pond can be in the range of 40-60°C. The temperature at the bottom of the pond can reach up to 90°C. Low-grade heat ( < 100°C) from solar ponds is currently converted into electricity by organic Rankine cycle engines. Thermoelectric generators can operate at very low temperature differences and can be a good candidate to replace organic Rankine cycle engines for power generation from salinity gradient solar ponds. The temperature difference in a solar pond can be used to power thermoelectric generators for electricity production. This paper presents an experimental investigation of a thermoelectric generators heat exchanger system designed to be powered by the hot water from the lower convective zone of a solar pond, and cold water from the upper convective zone of a solar pond. The results obtained have indicated significant prospects of such a system to generate power from low-grade heat for remote area power supply systems

Power Generation from Waste Heat Using Heat Pipe and Thermoelectric Generator

AbstractThis paper presents the investigation of power generation using the combination of heat pipes and thermo-electric generators. A majority of thermal energy in the industry is dissipated as waste heat to the environment. This waste heat can be utilized further for power generation. The related problems of global warming and dwindling fossil fuel supplies has led to improving the efficiency of any industrial process being a priority. One method to improve the efficiency is to develop methods to utilize waste heat that is usually wasted. Two promising technologies that were found to be useful for this purpose were thermoelectric generators and heat pipes. Therefore, this project involved making a bench type, proof of concept model of power production by thermoelectric generators using heat pipes and simulated hot air. The laboratory experiment of the proposed system was obtained with a counter flow air duct heat exchanger. The results obtained show an increase in the ratio of mass flow rate in upper duct to lower duct has a positive effect on the overall system performance. A higher mass flow rate ratio results in a higher amount of heat transfer and higher power output. The proposed system can be used for waste heat recovery from the industry where thermal energy is used in their daily process

Experimental investigation of power generation from salinity gradient solar pond using thermoelectric generators for renewable energy application

Low grade heat (<100 °C) is currently converted into electricity by organic rankine cycle (ORC) engines. ORC engines require certain threshold to operate as the organic fluid generally boils at more than 50 °C, and fails to operate at lower temperature. Thermoelectric generators (TEGs) can operate at very low temperature differences and can be good candidate to replace ORC for power generation at low temperatures. In this paper, the potential of power generation from TEG and salinity-gradient solar pond (SGSP) was investigated. SGSP is capable of storing heat at temperature up to 80 °C. The temperature difference between the upper convective zone (UCZ) and lower convective zone (LCZ) of a SGSP can be in the range of 40 °C-60 °C. This temperature difference can be used to power thermoelectric generators (TEG) for electricity production. This paper present result of a TEG system designed to be powered by the hot and cold water from the SGSP. The system is capable of producing electricity even on cloudy days or at night as the SGSP acts as a thermal storage system. The results obtained have indicated significant prospects of such system to generate power from a low grade heat for remote area power supply