Experimental and Numerical Study of Thermal Performance of an Innovative Waste Heat Recovery System (original) (raw)
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Development of a Waste Heat Recovery System
Journal of Engineering and Sustainable Development, 2018
In this work, focus is taken on developing a waste heat recovery system for capturing potential of exhaust heat from an air conditioner unit to be reused later. This system has the ability to store heat in phase change material (PCM) and then release it to a discharge water system when required. To achieve this goal, a Finned, Water-PCM, Double tube (FWD) system has been developed and tested. Spiral fins attached to the (FWD) system have been investigated for increasing the thermal conductivity of the PCM with and without copper network (CN). An experimental test rig that attached to an air-conditioner unit has been built to include 32 tubes of the FWD systems for both vertical and horizontal layouts during charging and water discharging processes. Transient 3-D, numerical simulations using (ANSYS Fluent14.0 software) have been developed to predict the thermal behavior for all types of FWD systems under investigation. Results show a significant performance improvement when using spiral fins with 6% (CN) during charging process at vertical position. As compared to the WFWD system, the FWD systems have been found to increase the PCM temperature gain of about 15.3 for SFWD system; 18.6% for SFWD system with 6% (CN) during charging process.
Numerical analysis and simulation of the heat recovery from wastewater using heat exchanger
MATEC Web of Conferences
The problem of global warming and the reduction of energy consumption have led to an evolutionary progress of research directed towards finding as many solutions as possible to these environmental issues. Firstly, this paper presents the background information on the role of wastewater as a source of heat for the future. Next, the paper includes the analysis elements that define a system for recovering thermal energy from wastewater. The main objective was to identify the parameters that determine the heat transfer. It has started from a conceptual model of the technological system that involves inputs and outputs characterized by technological, physical-chemical, measurable or imposed properties. In the second part this paper presents a numerical model elaborated for the analysis and simulation of the main physical processes, the mass and heat transfer, which underlie the operation of the heat pipe heat exchangers (HPHE). The numerical simulation of heat and mass transfer in the HPHE is computed by using Delphi 7 solver program. This program contained a series of sub-programs for the meshing of the field occupied by the HPHE, another subprogram for solving the meshing equations and the third for post processing. The design of HPHE is the key to provide a heat exchanger system to work proficient as expected. Finally, the result is used to optimize and improving heat recovery systems of the increasing demand for energy efficiency in residential buildings or industry.
IJSRST173188 | Waste Heat Recovery Systems for Refrigeration-A Review
2017
During various industrial processes, as much as 20 to 50% of the energy consumed is ultimately lost via waste heat contained in streams of hot exhaust gases, exhaust steam and hot liquids, as well as through heat transfer from hot equipment surfaces. Captured and reused waste heat is a valuable approach to improve overall energy efficiency by optimizing for costly purchased fuels or electricity and for the protection of global environment from pollution and rate of global warming. The applications of waste heat energy include generating electricity, preheating combustion air, space heating, refrigeration, etc. This review paper studies how refrigeration can be achieved quantitatively as well as qualitatively in different domains by using various waste heat recovery technologies from key industrial waste heat sources. This paper also studies the huge annual energy savings and environmental benefits that can be resulted by using these waste heat recovery technologies for refrigeration.
Experimental Investigation of Heat Pipe Heat Exchanger (Hphe) for Waste Heat Recovery Application
Proceeding of 4th Thermal and Fluids Engineering Conference, 2019
Due to environmental concern and the high price of the fuel, waste heat recovery has become a central issue for the industrial and commercial energy user. A large portion of the waste heat comes out as low-grade energy and with the conventional energy recovery technology, it is hard to justify economically. Heat pipe heat exchanger (HPHE) could be employed in this regard to recovering waste heat economically. In this study, a HPHE consisting of heat pipes arranged in stages has been developed where the heat pipes were constructed with the copper tube by attaching the fin (seven in each heat pipe), making the vacuum, injecting the water as fluid then finally heating and sealed it up. The heat pipes were constructed without any wick and works based on the thermosyphon principle and assembled vertically. The constructed HPHE was placed between two ducts carrying hot and cold fluid. The cold fluid was atmospheric air and temperature of the hot fluid was varied from 56-66°C. Performance of the HPHE was evaluated by analyzing heat transfer rate, heat transfer coefficient, and effectiveness. Effect of the filling ratio of water inside the heat pipe was also evaluated and the test was conducted for different air flow rate. The maximum performance of the HPHE was found with 45% filling ratio but it depends on the environmental conditions. The performance of the HPHE was found to increase with the increase of the hot air flow rate.
Parametric Study on a Novel Waste Heat Recovery System
2013
The present thesis is based on an industry-sponsor project involving a novel waste heat-to-electricity conversion system. This proprietary system utilizes thermal energy from a low temperature heat sources to produce torque that drives an electric generator to produce electricity. The system needs to be studied through scientific research to help with optimizing the product development, component design, and overall system performance. The main objectives of this study are to develop simulation tools (numerical model) that will allow to simulate the thermo-fluid processes in various system components and to use this numerical model to study the heat transfer and phase-change processes along with the work interactions. In the first part of this study, a novel numerical model was developed using the commercial CFD software Fluent. The novelty of this model was its capability to simultaneously simulate the phase-change and moving boundary processes. To the best of our knowledge, this i...
Role of Heat Pipe Heat Exchanger In Waste Heat Recovery
2018
The most of Industries using energy which is in the form of heat energy especially the steel industry using energy which is the heat energy. The need of waste heat recovery play the vital role in the contribution of reduction the production cost as well as the greenhouse gas effect .In this paper the innovative waste heat recovery system is described which is the design, manufacturing, testing of Flat Pipe Heat Exchanger. The thermal performs of FHP is studied in laboratory as well as in Industry which will give the potential of Heat Pipe Heat Exchanger in waste heat recovery. The comparison is made between actual and theoretical results .From result concluded that the Heat Pipe Heat Exchanger gives maximum contribution for waste heat recovery in industry
Identification of the Most Effective Heat Exchanger for Waste Heat Recovery
Chemical Engineering Transactions, 2015
Laboratory of Energy Intensive Processes placed in the building of NETME Centre, Faculty of Mechanical Engineering, Brno University of Technology, is a research laboratory focused on increasing efficiency of industrial plants. Current research in the laboratory focuses on improving of the energy efficiency of industrial laundries. That can be achieved for example by recovery of the heat produced in the process. A microturbine is used as a power source. It produces flue gas with temperature approximately 300 °C. This flue gas is currently leaving into ambient air without utilization of its heat. Temperature this high enables utilization of the waste heat for preheating the combustion air or for heating water for various purposes. In this article, an evaluation procedure of several types (both conventional and special) of heat exchangers that are suitable for utilization of flue gas' waste heat and the possibilities of their intensification will be described. It will be shown that...
EXPERIMENTAL AND THEORTICAL STUDY OF THE THERMAL PERFORMANCE OF HEAT PIPE HEAT EXCHANGER
Heat pipe heat exchanger (HPHE) considers one of the most useful devices for the recovery of waste heat energy. An Experimental study has been carried out on air to –air HPHE constructed of thermosyphon heat pipes with distilled water as the working fluid and a fill ratio of 75% from the evaporator length. Its model was composed of 4 rows, each row contains 12 copper tubes, each tube have ID= 9.5 mm, OD=10mm and length =950 mm and the rows of tubes were arranged in a staggered manner. Aluminum wavy plate fins of 0.1mm thickness were fixed among the tubes to increase the heat transfer area. Tests were conducted at various flow rates (air flow rate through evaporator and condenser sections) ranged between 0.12 and 0.37 kg/s and at different temperatures of air entering evaporator section (90, 100,110) to indicate discontinuity in the effectiveness when the flow rate ratio equal to one. The results show that the maximum value of effectiveness for the four heat pipe heat exchanger occurs when = 2. Theoretical model based on (ε-NTU) has been developed by using visual basic language computer program to analysis of the temperature distribution along heat pipe heat exchanger. The results from this model were compared with experimental results. A comparison between the experimental and theoretical results shows little discrepancy. : Effectiveness, : actual heat transfer rate (w), : maximum heat transfer rate (w), : total overall heat transfer (w/m 2 .k), : total area (m 2) , : minimum heat capacity rate (kJ/kg.k), : maximum heat transfer rate (kJ/kg.k), : number of transfer unit, : effectiveness of evaporator, : number of transfer unit for evaporator, : effectiveness of condenser, : number of transfer unit for condenser, : overall heat transfer coefficient of evaporator (w/m 2 .k), : heat transfer area of evaporator (m 2) , :heat capacity rate of evaporator (w/k). : Overall heat transfer coefficient of condenser (w/m 2 .k), : heat transfer area of condenser (m 2) , : heat capacity rate of condenser (w/k), : area of pipe (m 2), : diameter of pipe(m) , : length of pipe (m) , : thickness of fin (m), : number of fins per meter , : number of pipes, :pi (=3.14), : width of fin (m), : total thermal resistance of evaporator (k/w), : external thermal resistance of evaporator (k/w), : fouling thermal resistance of (k/w), : wall thermal resistance of evaporator (k/w), : internal thermal resistance of evaporator , : total thermal resistance of condenser(k/w), : external thermal resistance of evaporator (k/w), : fouling thermal resistance of condenser (k/w), : wall thermal resistance of condenser (k/w), : internal thermal resistance of condenser , : overall effectiveness, j= number of row.
2018
Due to environmental concern and high price of the fuel, waste heat recovery has become a central issue for industrial and commercial energy users. Heat pipe heat exchanger (HPHE) could be employed in this regard economically. In this study, an HPHE consisting of heat pipes arranged in stages has been developed. Water was used as the heat carrying fluid inside the heat pipe and square fins were used in the cooling and heating zone of the heat pipe. The constructed HPHE was placed between two ducts carrying hot and cold air. The hot fluid temperature was varied from 60 to 80 o C which resembles waste heat and cold air was atmospheric air. The hot and cold air’s mass flow rate was varied between 0.037 and 0.087 kg/s and heat transfer between two air streams were measured as 228.5 to 362.2W and heat transfer coefficient varies from 4.22 to 8.09 W/m 2 -K.
Comparison of low temperature waste heat recovery methods
Energy, 2017
Large amounts of heat is wasted through air coolers and water coolers for cooling low temperature (<150 °C) streams in many technologies. This paper summarizes the results of a study for partial substitute of air cooler, which cools down a hydrocarbon stream from 130 °C to 70 °C and dissipating heat of 12.1 MW into the environment, by applying organic Rankine cycle (ORC) and Kalina systems. Results showed that the heat energy (Q H) recovered in the evaporator were 8.0-8.6 MW for ORC using i-pentane as working fluid and 8.2-8.3 MW for Kalina cycle, respectively. Efficiency () of selected systems obtained at the highest power generated (W T) was 10.0% (W T = 862 kW) for ORC and 10.57% (W T = 996 kW) for Kalina cycle within the design boundaries. Calculated carbon dioxide (CO 2) emission reduction potential was 2 260 t/y for ORC and 2 600 t/y for Kalina system, respectively, at advantageous process conditions. Results showed that Kalina cycle provided higher efficiency and power generation ability on expense of higher system pressure (29 bar to 7 bar). Economic calculations showed that the payback time is about 5.0 year for both systems.