kW Of Heat Research Articles

Using of Local Heat Sources with Warm-Water Heat Exchanger for Combustion of Wood Biomass in Low Temperature Heating Systems

Biomass as fuel is used for many years. At present it is important to effectively use energy sources because price of energy is more and more expensive. This is the main reason for building of modern low-energy houses. The projected thermal performance of these buildings rarely exceeds 4-6 kW. During most days of heating season these buildings need only 2-4 kW of heat but almost all produced heat sources have nominal thermal power higher than 10-15 kW. Because of this the thermal power of majority heat sources is oversized and using of them could be complicated. One of the solutions of this problem should be heat storage in accumulation vessels. The paper deals about using of local heat source with warm-water heat exchanger for combustion of wood biomass. There were tested thermal and emissions parameters of wood stoves. There was measured thermal power to air and to the accumulation vessels, production of carbon monoxide (CO), production of nitrogen oxides (NOx) and production of particulate matters (PM). The results shows that local heat sources with warm-water heat exchanger for combustion of wood biomass could be used for heating of new low-energy buildings.

The Thermosiphon Cooling System of the ATLAS Experiment at the CERN Large Hadron Collider

Abstract The silicon tracker of the ATLAS experiment at CERN Large Hadron Collider will operate around –15°C to minimize the effects of radiation damage. The present cooling system is based on a conventional evaporative circuit, removing around 60 kW of heat dissipated by the silicon sensors and their local electronics. The compressors in the present circuit have proved less reliable than originally hoped, and will be replaced with a thermosiphon. The working principle of the thermosiphon uses gravity to circulate the coolant without any mechanical components (compressors or pumps) in the primary coolant circuit. The fluorocarbon coolant will be condensed at a temperature and pressure lower than those in the on-detector evaporators, but at a higher altitude, taking advantage of the 92 m height difference between the underground experiment and the services located on the surface. An extensive campaign of tests, detailed in this paper, was performed using two small-scale thermosiphon systems. These tests confirmed the design specifications of the full-scale plant and demonstrated operation over the temperature range required for ATLAS. During the testing phase the system has demonstrated unattended long-term stable running over a period of several weeks. The commissioning of the full scale thermosiphon is ongoing, with full operation planned for late 2015.

A Parametric Study on Exergy and Exergoeconomic Analysis of a Diesel Engine based Combined Heat and Power System

This paper presents exergy and exergoeconomic analysis and parametric study of a Diesel engine based Combined Heat and Power (CHP) system that produces 277 kW of electricity and 282 kW of heat. For this purpose, the CHP system is first thermodynamically analyzed through energy and exergy. Then cost balances and auxiliary equations are applied to subsystems. The exergoeconomic analysis is based on specific exergy costing (SPECO) method. Finally a parametric study is used to show effect of ambient temperature on important energy, exergy and exergoeconomic parameters of the CHP system. Also effects of change in compressor pressure ratio and turbine inlet temperature on these parameters are investigated in different environment temperatures. The results show that increasing ambient temperature increases the work output, heating power and exergoeconomic factor and decreases the exergetic efficiency and cost of exergy destruction. Increasing compressor pressure ratio leads to increase in the work output, heating power, exergetic efficiency, and exergy destruction cost and exergoeconomic factor of the CHP system in all environment temperatures. Also increasing turbine inlet temperature decreases the work output, exergetic efficiency and exergoeconomic factor while increases the heating power as well as exergy destruction cost in all environment temperatures.

Design and experimental analysis of an efficient HVAC (heating, ventilation, air-conditioning) system on an electric bus with dynamic on-road wireless charging

The design, control and experimental verification of an HVAC (heating, ventilation, air-conditioning) system to achieve high operational efficiency for an electric bus equipped with a dynamic wireless charging capability are described in this paper. Target power capacities of the HVAC system have been set as 28 kW of cooling and 26 kW of heating with a 600 V in-vehicle environment with COPs (coefficient of performance) of more than 1.6 for cooling and 2.6 for heating, which are required for customer's comfort. For an efficient HVAC system design, an integrated air-conditioning with a heat pump system is proposed and analyzed to meet the objectives of the HVAC system, incorporating the waste heat recovery from the drive motor, its driver, and other wireless charging electric modules. In addition, a control algorithm for operational energy management, considering the real-time power consumption and the wirelessly delivered power, is also proposed and verified to secure an actual operational energy consumption target. Through the component- and vehicle-level of the experimental performance verification, combined with energy demand dynamic model, the proposed HVAC system is verified experimentally to meet target power capacities and efficiency measures for cooling and heating, which are important to electric buses, especially with dynamic wireless charging capability.

Evaluating the performance of a large borehole ground source heat pump for greenhouses in northern Japan

Abstract The objective of this study was to use both field data and a numerical simulation to examine the long-term performance and environmental effects of a large GSHP (ground source heat pump) system that heats and cools industrial greenhouses in a cold region. A large vertical GSHP system was installed in the city of Akabira in the north of Hokkaido, Japan to provide heating and cooling for 12 greenhouses. The system has a maximum capacity of 640 and 648 kW for heating and cooling, respectively. The system was monitored and analyzed from Oct. 2010 through May 2011. The system had a COP (coefficient of performance) of 3.0 and SCOP (system coefficient of performance) of 2.7. The average heat extraction rate of the system was approximately 27.7 W/m. In addition, the ground temperature at a depth of 40 m decreased from approximately 7.8 °C to 0 °C after 8 months of operation. A numerical model of the system was developed in FEFLOW to predict its future behavior under conditions where the demand for heating surpasses the demand for cooling. The simulation results suggest that the system could maintain the heat exchange rate for several years without significantly compromising its performance. The risk of operating the system under unbalanced heating and cooling loads was addressed via case studies. Groundwater flow decreases the risk of operating the system when the heat extraction was much higher or lower than the heat injection.

Performance investigation on a multi-unit heat pump for simultaneous temperature and humidity control

A multi-unit heat pump is presented for simultaneous humidity and temperature control to improve the energy efficiency and the thermal comfort. Two parallel connected condensers are employed in the system, locating at the back of the indoor evaporator and the outdoor unit, respectively. The heat pump can operate in four modes, including heating, cooling and dehumidification without and/or with partial or total condensing heat recovery. The experimental investigation shows that the temperature control capacity is from 3.5kW for cooling to 3.8kW for heating with the cooling and heating efficiency higher than 3.5kWkW−1, and the dehumidification rate is about 2.0kgh−1 with the efficiency about 2.0kgh−1kW−1. The supply air temperature and humidity can be simultaneously regulated with high accuracy and high efficiency by adjusting the indoor and/or outdoor air volumes. It provides an integrated and effective solution for simultaneous indoor air temperature and humidity control for all-year-round operation in residential buildings.

Exergy and exergoeconomic analysis and optimisation of diesel engine based Combined Heat and Power (CHP) system using genetic algorithm

In the present study, a diesel engine based Combined Heat and Power (CHP) system is optimised using exergoeconomic concept and genetic algorithm. For this purpose, the CHP system is first thermodynamically analysed through energy and exergy. Then cost balances and auxiliary equations are applied to subsystems. Finally an objective function representing fuel cost, cost of exergy loss and destruction and purchase and maintenance cost of the system components is considered for the optimisation study. Furthermore the above procedure is applied for a case study that produces 277 kW of electricity and 282 kW of heat. Also exergetic and exergoeconomic parameters are calculated in optimum case and compared with the base case. The results show that by applying the optimisation approach for our case study, 8.02% reduction in objective function is achieved which is might be considerable in CHP systems optimisation.

엔진 배기열 이용 유기랭킨사이클에 대한 실험적 연구

본 연구에서는 산업용 가스 엔진의 배기 폐열을 회수하여 발전하는 유기랭킨사이클을 구성하고 시스템 성능 분석 실험을 수행하였다. 엔진 배기가스 열을 작동유체(냉매 R134a)에 흡수시키기 위해 Shell & Tube 방식 열교환기를 엔진 배기 매니폴드 후단에 장착하였다. 엔진출력 60 kW인 조건에서 약 63 kW의 배기가스 열을 배출하였으며, 열교환기를 통해 작동유체에 흡수된 열량은 43~46 kW로서 배기가스 열회수율은 68~73%, 최대출력은 4.6 kW로서 배기가스 열량에 대한 최대출력의 비는 7.3%을 나타내었다. In this study, an organic Rankine cycle(ORC) for gas engine waste heat recovery for industry has been constructed and a performance analysis test has been carried out. Shell & tube style heat exchanger has been equipped on an engine exhaust manifold in order to absorb heat of engine exhaust gas into the working fluid(refrigerant R134a). Under 60 kW of engine power output, about 63 kW of engine exhaust gas heat was discharged and the proportion of heat recovered was 68~73% while 43~46 kW of heat was absorbed into working fluid. Consequently rated power output of ORC was 4.6 kW while the ratio of rated power output to engine exhaust gas heat was 7.3%.

Design strategy for a Chemical Looping Combustion system using process simulation and Computational Fluid Dynamics

A strategy for design and optimisation of chemical processes involving multiple fluidised bed reactors is presented through a combination of standard design calculations, process simulation and Computational Fluid Dynamics (CFD). The strategy is demonstrated in designing a Chemical Looping Combustion (CLC) process that generates 12.5 kW of heat in the air reactor. The resulting design strategy will allow for very economical investigations into various design and optimisation considerations. It also offers a platform from which to conduct virtual prototyping investigations for new process concepts, which will lead to significant economic benefits when compared with a traditional experimental process development strategy.

Development of a hydrogen catalytic heater for heating metal hydride hydrogen storage systems

This paper describes the design, fabrication and performance evaluation of a high efficiency, compact heater that uses the catalytic oxidation of hydrogen to provide heat to a hydrogen storage system. The heater was designed to transfer up to 30 kW of heat from the catalytic reaction to the hydrogen storage system via a recirculating heat transfer fluid. The catalytic heater consists of three main parts: 1) the reactor, 2) the gas heat recuperator, and 3) oil and gas flow distribution manifolds. The reactor and recuperator are integrated, compact, finned-plate heat exchangers to maximize heat transfer efficiency and minimize mass and volume. Detailed, three-dimensional, multi-physics computational models were used to design and optimize the system. At full power the heater was able to catalytically combust a 10% hydrogen/air mixture flowing at over 80 cubic feet per minute and transfer 30 kW of heat to a 30 gallon per minute flow of oil over a temperature range from 100 °C to 220 °C. The total efficiency of the catalytic heater, defined as the heat transferred to the oil divided by the inlet hydrogen chemical energy, was determined to exceed the design goal of 80% for oil temperatures from 60 °C to 165 °C.

Performance analysis of a trigeneration system based on a micro gas turbine and an air-cooled, indirect fired, ammonia–water absorption chiller

The objective of this paper is to experimentally determine the efficiency and viability of the performance of an advanced trigeneration system that consists of a micro gas turbine in which the exhaust gases heat hot thermal oil to produce cooling with an air cooled absorption chiller and hot water for heating and DHW. The micro gas turbine with a net power of 28 kW produces around 60 kW of heat to drive an ammonia/water air-cooled absorption chiller with a rated capacity of 17 kW. The trigeneration system was tested in different operating conditions by varying the output power of the micro gas turbine, the ambient temperature for the absorption unit, the chilled water outlet temperature and the thermal oil inlet temperature. The modelling performance of the trigeneration system and the electrical modelling of the micro gas turbine are presented and compared with experimental results. Finally, the primary energy saving and the economic analysis show the advantages and drawbacks of this trigeneration configuration.

Performance and efficiency of a biogas CHP system utilizing a stirling engine

A Stirling engine utilizes external combustion to produce heat and electricity. Due to the external combustion chamber, the engine can utilize a multitude of fuels including biogas or natural gas. The system used in this study is capable of producing about 7 kW of heat and 1 kW of electricity. Nitrogen is used as the “working fluid” in the engine. The heat from the combustion chamber is circulated through a cooling system making use of the thermal energy. The system includes a battery bank for energy storage and has been equipped with various instruments used to measure temperatures, pressures and flow rates of the fuel, the combustion air and the coolant. The engine is operated using natural gas as well as biogas and the engine characteristics for each are compared. The data collected is used to determine the system performance, thermal and electrical power outputs, individual and overall efficiencies, as well as exhaust emissions (O2, CO, CO2, NOx and HC). This paper will present a detailed description of the CHP system, the instrumentation, the test procedures, the test data, analysis of the results and comparison of the biogas and natural gas test results.

Low‐cost thermoacoustic co‐generator for biomass‐burning cook stoves.

Three billion people cook daily on an open fire or primitive stove that creates so much pollution that it has been shown to be directly responsible for 1.6×106 deaths each year, almost exclusively among women and young children. Atmospheric models suggest that black carbon and methane released during biomass combustion are also the primary anthropogenic contribution to global warming from the populations of Southeast Asia, sub‐Saharan Africa, and India. Recent research demonstrates that fan‐aided combustion creates a significant decrease in products of incomplete combustion that degrades indoor air quality and exacerbates global warming. The use of a fan also increases efficiency, improves fuel flexibility, and reduces cooking times. Unfortunately, 1.6×109 biomass burners have no access to electricity, yet each cook stove produces 4–8 kW of heat. This presentation will describe a very simple co‐generator prototype that extracts a small fraction of the stove’s heat and uses air at atmospheric pressure in a lumped‐element, stack‐based, thermoacoustic engine to vibrate an inexpensive moving‐coil electrodynamic loudspeaker acting as a linear alternator that can generate the few watts of electrical power necessary to operate the fan and charge a battery. [Work supported by Paul S. Veneklasen Research Foundation.]

Materials issues in the development of a long life alkaline fuel cell electrode

Typical domestic requirements call for system capable of outputting about 1 kW of electrical power on a continuous or intermittent basis and about 1 kW of heat. The alkaline fuel cell approach is suitable because of its potential for low cost and ruggedness. Apart from the issue of overall cost, the principal technical issue is to develop a cost effective long life 40,000 hour electrode. In this article we describe the construction of electrodes from Ni metal powder by compression and electroless deposition of Ni metal, effectively sintering the particles. These techniques can be applied to very high surface area Ni nano particles which should dramatically improve the electrode performance.

Coupled fluid/structure analyses of the MEGAPIE spallation source target during transients

The paper describes some R&D activities undertaken in support of the design and safe operation of MEGAPIE (MEGAwatt PIlot Experiment) spallation source target, which is scheduled to be irradiated by a proton beam in the SINQ facility at the Paul Scherrer Institute in 2006. The target material is lead bismuth eutectic (LBE), which also acts as the primary coolant. As a consequence of the spallation reactions, about 600 kW of heat would be deposited in the target during operation, and considerable R&D effort is being expended to demonstrate continuing coolability and structural integrity under a variety of operational and abnormal conditions. The paper gives three examples of transient analyses carried out as part of the safety assessment of the target: (1) a beamline trip and recovery; (2) failure of the primary electro-magnetic pump (EMP); (3) failure of the secondary EMP (used to cool the base of the target). The study involves the simultaneous application of a system-analysis code, in our case a version of RELAP5, a computational fluid dynamics (CFD) tool (CFX-4), and a structural analysis code (ABAQUS). The RELAP5 code is used to provide transient boundary conditions for a localized conjugate heat transfer analysis of the lower target region, undertaken using CFD, and includes the feed-back effects arising from the secondary cooling and control systems. A conjugate heat transfer problem is then solved using CFD, which provides time-dependent thermal and flow data within the LBE, together with the thermal and mechanical loads to the target structures. Finally, an in-house interface program is employed to transfer mesh geometry, model topology and (time-dependent) thermal/mechanical data to enable stress analysis of the principal lower-target structural components to be performed. It is demonstrated that none of the transients considered result in critical stress conditions occurring in the target components, but that further operation is not recommended unless both pumps are fully operational.

Thermal hydraulic studies of spallation target for one-way coupled indian accelerator driven systems with low energy proton beam

BARC has recently proposed a one-way coupled ADS reactor. This reactor requires typically ∼1 GeV proton beam with 2 mA of current. Approximately 8 kW of heat is deposited in the window of the target. Circulating liquid metal target (lead/lead-bismuth-eutectic) has to extract this heat and this is a critical R&D problem to be solved. At present there are very few accelerators, which can give few mA and high-energy proton beam. However, accelerators with low energy and hundreds of micro-ampere current are commercially available. In view of this, it is proposed in this paper to simulate beam window heating of ∼8 kW in the target with low-energy proton beam. Detailed thermal analysis in the spallation and window region has been carried out to study the capability of heat extraction by circulating LBE for a typical target loop with a proton beam of 30 MeV energy and current of 0.267 mA. The heat deposition study is carried out using FLUKA code and flow analysis by CFD code. The detailed analysis of this work is presented in this paper.

Materials issues in the development of a long life alkaline fuel cell electrode

Typical domestic requirements call for system capable of outputting about 1 kW of electrical power on a continuous or intermittent basis and about 1 kW of heat. The alkaline fuel cell approach is suitable because of its potential for low cost and ruggedness. Apart from the issue of overall cost, the principal technical issue is to develop a cost effective long life 40,000 hour electrode. In this article we describe the construction of electrodes from Ni metal powder by compression and electroless deposition of Ni metal, effectively sintering the particles. These techniques can be applied to very high surface area Ni nano particles which should dramatically improve the electrode performance.

Study of a small heat and power PEM fuel cell system generator

A micro-cogenerator based on a natural gas reformer and a PEMFC is studied in its entirety, pointing out the links between different sub-systems. The study is conducted within the EPACOP project, which aims at testing PEMFC systems on user sites to evaluate development and acceptance of this technology for small stationary applications. Five units were installed from November 2002 to May 2003 and have been operated until now, in real life conditions. They deliver up to 4 kW of AC power and about 6 kW of heat. Center for Energy and Processes (CEP), one of the scientific partners, processes and analyses the experimental data from the five units, running in different regions of France. This database and the study of the flowsheet enable to propose changes to enhance the efficiency of the system composed of a steam reforming, a shift and a preferential oxidation reactor, a fuel cell stack and heat exchangers. The steady state modelling and optimisation of the system is done with Thermoptim ®, a software developed within CEP for applied thermodynamics. At constant power, main targets are to decrease natural gas consumption, to increase heat recovery and to improve the water balance. This study is made using the pinch point analysis, at full load and partial load. Main results of this study are different system configurations that allow improvement of gross electrical and thermal efficiency and enable to obtain a positive water balance.

CFD Design Support at PSI for the International MEGAPIE Liquid-Metal Spallation Target

The MEGAPIE (Megawatt Pilot Experiment) Project has been primarily initiated in response to interest in the Accelerator Driven System (ADS). The ADS is a nuclear reactor concept with a fuel cycle which can burn minor actinide waste products from conventional reactors, while also taking advantage of the safety characteristics of a sub-critical reaction process. By this means, the fission chain reaction is maintained by additional neutrons generated by protons in a liquid-metal spallation target. The goal of the international MEGAPIE project is to design and construct such a target and install and test it over a period of one year in the SINQ spallation neuron source facility at the Paul Scherrer Institut (PSI). To aid the design process, Computational Fluid Dynamics (CFD) is being used to optimise the thermal- hydraulic behaviour of the target. Results obtained so far indicate that it should be possible to remove 700 kW of heat deposited by the proton beam in the target, under steady-state conditions (40kg/s total Lead Bismuth Eutectic flow rate), without peak window temperature rising above about 385°C, when using a bypass flow of 2.5 kg/s and a slanted- end guide tube. A tentative peak window temperature of 400°C is currently considered allowable, on the basis of material strength after irradiation, and CFD simulation is currently being validated by suitable LBE experiments in similar geometry.

CFD Design Support at PSI for the International MEGAPIE Liquid-Metal Spallation Target

The MEGAPIE (Megawatt Pilot Experiment) Project has been primarily initiated in response to interest in the Accelerator Driven System (ADS). The ADS is a nuclear reactor concept with a fuel cycle which can burn minor actinide waste products from conventional reactors, while also taking advantage of the safety characteristics of a sub-critical reaction process. By this means, the fission chain reaction is maintained by additional neutrons generated by protons in a liquid-metal spallation target. The goal of the international MEGAPIE project is to design and construct such a target and install and test it over a period of one year in the SINQ spallation neuron source facility at the Paul Scherrer Institut (PSI). To aid the design process, Computational Fluid Dynamics (CFD) is being used to optimise the thermal-hydraulic behaviour of the target. Results obtained so far indicate that it should be possible to remove 700 kW of heat deposited by the proton beam in the target, under steady-state conditions (40kg/s total Lead Bismuth Eutectic flow rate), without peak window temperature rising above about 385°C, when using a bypass flow of 2.5 kg/s and a slanted-end guide tube. A tentative peak window temperature of 400°C is currently considered allowable, on the basis of material strength after irradiation, and CFD simulation is currently being validated by suitable LBE experiments in similar geometry.