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Characterization of a new total heat recovery system using CaCl_(2) as working fluid:Thermal modeling and physical analysis

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Energy and Built Environment 2022年第2期3卷 158-170页

作者： Chenghu Zhang Yibo Zhao Xiaomeng Shi Xinpeng Huang School of Architecture Harbin Institute of TechnologyHarbinHeilongjiangPR China

This paper introduces a kind of open cycle absorption heat wet flue gas heat recovery system,which use CaCl_(2) as the working *** system will use the wet heat recovery method and combined with an efficient heat pump system for flue gas as a heat source *** direct contact with the solution in the absorber,the flue gas is going to carry out gas,liquid heat transfer between heat exchanger,realization of sensible heat and latent heat step by *** the key part of the system,absorber is established by one-dimensional steady-state heat transfer and mass transfer *** paper uses the finite difference method to model the discrete numerical methods,and an-alyzes the characteristics of heat and mass transfer in the *** obtain the concentration curves of the three kinds of working medium’s temperature and flow along the height *** also analyze the influence of CaCl_(2) solution parameters changes on the absorption process,parsing the reason of the temperature change by analyzing the three working medium’s energy flow *** found that the temperature change of flue gas is non-monotonic,which decreases gradually in the range of absorption tower height 0-0.9 m,and then increases *** reason for this change is that sensible heat exchange and latent heat exchange exist between flue gas and *** such a change has an impact on the efficiency of the system,it prevents the"white smoke"from condensing in the air,which effectively protects the *** with conventional LiBr absorption heat pump,the system constructed in this paper has certain advantages in latent heat recovery,flue gas heat energy utilization,energy conservation and emission reduction and economy.

关键词： Hot and wet waste gas waste heat recovery heat and mass transfer System features

Simulation of CO_2 Brayton Cycle for Engine Exhaust heat recovery under Various Operating Loads

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Transactions of Tianjin University 2015年第3期21卷 193-198页

作者：舒歌群张承宇田华高媛媛李团兵仇荣赓 State Key Laboratory of Engines Tianjin University

A bottoming cycle system based on CO2 Brayton cycle is proposed to recover the engine exhaust heat. Its performance is compared with the conventional air Brayton cycle under five typical engine conditions. The results show that CO2 Brayton cycle proves to be superior to the air Brayton cycle in terms of the system net output power, thermal efficiency and recovery efficiency. In most cases, the recovery efficiency of CO2 Brayton cycle can be higher than 9% and the system has a better performance at the engine＇s high operating load, The thermal efficiency can be as large as 24.83% under 100% olaerating load, accordingly, the net outnut nower of 14.86 kW in nhtnined

关键词： CO2 Brayton cycle waste heat recovery

Experimental investigation on diesel engine's waste heat capacity under mapping characteristics

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Science China(Technological Sciences) 2015年第1期58卷 9-18页

作者： TIAN Hua ZHANG ChengYu LI XiaoNing SHU GeQun State Key Laboratory of Engines Tianjin University

waste heat recovery for internal combustion engine(ICE)has been considered as an important strategy to improve efficiency and promote fuel economy,thus alleviating the problems of energy shortage and environmental *** paper investigates the characteristics of various kinds of waste heat energy,namely,waste heat in exhaust,cooling water and charge air,over the engine’s whole operating *** on the energy balance experiments,the energy distribution of a conventional heavy-duty diesel engine is obtained under mapping *** to exergy analysis,the energy recovery potential for waste heat is studied as *** experimental results indicate that exhaust energy increases with engine speed and load,while cooling water energy is more sensitive to load,especially at low and middle *** air energy,on the other hand,mainly counts on speed rather than *** energy possesses the highest recovery potential in terms of both quantity and *** waste heat recovery,a dramatic improvement in engine efficiency is achievable,actually,the maximum value can amount to 60%or even more.

关键词： waste heat recovery mapping characteristics diesel engine energy balance exergy analysis

Overall efficiency optimization of controllable mechanical turbo-compounding system for heavy duty diesel engines

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Science China(Technological Sciences) 2017年第1期60卷 36-50页

作者： HE GuanZhang XIE Hui HE ShiJie State Key Laboratory of Engines Tianjin University Tianjin 300072 China School of Mechanical Engineering Tianjin University Tianjin 300072 China

A controllable mechanical turbo-compounding(CMTC) system including continuously variable transmission(CVT) and power turbine bypass valve is proposed to recover waste heat from engine exhaust. The combined matching principle considering swallowing capacity of both charging turbine and power turbine, main gear ratio is investigated at first based on the analysis of individual influence. Then the effects and strategies of CVT and power turbine bypass valve are studied for better performance under off-design conditions. At last, the transient response of intake pressure of engine with CMTC system is researched and the fuel saving potential is tested under driving cycle conditions. The results indicate that the overall fuel efficiency elevates at the off-design conditions if CVT is adopted due to the improvement of power turbine operating efficiency by speed modulation. The diversion of exhaust through power turbine bypass valve under the low load condition is necessary. The back pressure of the charging turbine infuences the transient response of intake pressure for a fixed CMTC configuration. A method featured by the assistance of power turbine bypass valve is tested to improve the transient response of the intake pressure. The fuel consumption reduces by 2% and 3.4% under highway fuel economy test(HWFET) and Tianjin 503(TJ503) driving cycles respectively.

关键词： heavy duty diesel engine waste heat recovery controllable mechanical turbo-compounding continuously variabletransmission device driving cycle transient response

Modelling and Thermodynamic Analysis of a Hot-Cold Conversion Pipe Using R134a-DMF-He as the Working Pair

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Journal of Thermal Science 2021年第1期30卷 64-75页

作者： LI Haiyu LIN Peng DU Shuai WANG Liwei Institute of Refrigeration and Cryogenics Shanghai Jiao Tong UniversityShanghai 200240China China Ship Development and Design Center Shanghai 201108China

Based on the concept of a diffusion absorption system,a hot-cold conversion pipe utilizing 1,1,1,2-tetrafluoroethane(R134 a)-dimethylformamide(DMF)-helium(He)as the working pair is presented with the aim of cooling output by recovering the low-grade waste *** model of the hot-cold conversion pipe is established,in which a heat pipe is used to transfer the waste heat as the heat *** equations of the thermodynamic properties of the working pair are established by equation of state method(EOS).The model of the hot-cold conversion pipe is built based on the mass,species and energy balance equations of each *** direct conversion of heat to cold is achieved by the desorption,absorption,condensation and diffusion evaporation processes of R134 *** hot-cold conversion pipe is cooled by natural convection,which can be enhanced by chimney *** thermodynamic analysis is carried out to analyze the effect of the boundary conditions,*** heat source temperature,the refrigeration temperature,and the environmental temperature,on the system *** paper provides a theoretical basis for actual application of the hot-cold conversion pipe in waste heat recovery field.

关键词： diffusion absorption refrigeration R134a-DMF-He hot-cold conversion waste heat recovery thermodynamic analysis

Prime Mover Capacity Optimization and Thermodynamic Performance Analysis of Internal Combustion Engine Based CCHP System

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Journal of Thermal Science 2023年第4期32卷 1583-1594页

作者： WANG Shucheng MUHAMMAD Imran LI Hongwei CHEN Xiaoxu QIN Mei School of Energy and Power Engineering Northeast Electric Power UniversityJilin132012China College of Engineering and Physical Sciences MechanicalBiomedical and Design EngineeringAston UniversityBirminghamB47ETUK Northeast Electric Power Design Institute Co. Ltd.of China Power Engineering Consulting GroupChangchun130021China

In this research,a solar hybrid combined cooling heating and power(CCHP)system is proposed considering the different scenarios of Prime Movers(PMs)and the part-load performance of PMs is validated by the designed values from the manufacturer of ***,a multi-optimization model based on a genetic algorithm is developed in order to select both the most promising performance PM and the most cost-effectiveness,environmentally friendly number of collectors for the proposed CCHP system,*** the hourly performance of this solar hybrid CCHP is determined through a case study of a hotel in *** show that the highest efficiency of the PM with larger capacity has the most promising performance and the collector number of 90 turns out to be a superior value for the hotel building based on the primary energy saving ratio of 61.61%.Moreover,on a typical summer day,the recovered waste heat and the solar energy can provide all the thermal energy demands,while,an auxiliary boiler should be started to fulfill the energy gap in both typical transition and winter *** the simulation result,the CO_(2) emissions can be reduced by 856.2 t/a due to the solar energy introduced into the ***,the dynamic investment payback period will change from 3.01 years to 3.56 years when the fuel price(P_(fuel))ranges from 0.8P_(fuel) to1.2P_(fuel).

关键词： combined cooling heating and power(CCHP)system distributed energy system optimization waste heat recovery ICE

Optimization of Low-Temperature Exhaust Gas waste heat Fueled Organic Rankine Cycle

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Journal of Iron and Steel Research International 2012年第6期19卷 30-36页

作者： WANG Hui-tao WANG Hua ZHANG Zhu-ming Engineering Research Center of Metallurgical Energy Conservation and Emission Reduction Ministry of Education Kunming University of Science and TechnologyKunming 650093YunnanChina Kunming Iron and Steel Company Kunming 650302YunnanChina

Low temperature exhaust gases carrying large amount of waste heat are released by steel-making process and many other industries, Organic Rankine Cycles （ORCs） are proven to be the most promising technology to re- cover the low-temperature waste heat, thereby to get more financial benefits for these industries. The exergy analysis of ORC units driven by low-temperature exhaust gas waste heat and charged with dry and isentropic fluid was per- formed, and an intuitive approach with simple impressions was developed to calculate the performances of the ORC unit. Parameter optimization was conducted with turbine inlet temperature simplified as the variable and exergy effi- ciency or power output as the objective function by means of Penalty Function and Golden Section Searching algo- rithm based on the formulation of the optimization problem. The power generated by the optimized ORC unit can be nearly as twice as that generated by a non-optimized ORC unit. In addition, cycle parametric analysis was performed to examine the effects of thermodynamic parameters on the cycle performances such as thermal efficiency and exergy efficiency. It is proven that performance of ORC unit is mainly affected by the thermodynamic property of working fluid, the waste heat temperature, the pinch point temperature of the evaporator, the specific heat capacity of the heat carrier and the turbine inlet temperature under a given environment temperature.

关键词： waste heat recovery organic Rankine cycles optimization working fluid exergy pinch point

Flexible thermocells for utilization of body heat

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Nano Research 2014年第4期7卷 443-452页

作者： Hyeongwook Im Hyung Geun Moon Jeong Seok Lee In Young Chung Tae June Kang Yong Hyup Kim School of Mechanical and Aerospace Engineering Seoul National University Seoul 151-742 Republic of Korea Department of Electronics and Communications Engineering Kwangwook University Seou1139-701 Republic of Korea Department of Nanofusion Technology Pusan National University Busan 609-735 Republic of Korea

Plastic thermo-electrochemical ceils （thermocells） involving aqueous potassium ferricyanide/ferrocyanide electrolyte have been investigated as an alternative to conventional thermoelectrics for thermal energy harvesting. Plastic thermocells that consist of all pliable materials such as polyethylene terephthalate （PET）, fabrics, and wires are flexible enough to be wearable on the human body and to be wrapped around cylindrical shapes. The performance of the thermocells is enhanced by incorporating carbon nanotubes into activated carbon textiles, due to improved charge transfer at the interface. In cold weather conditions （a surrounding temperature of 5 ℃）, the thermocell generates a short-circuit current density of 0.39 A/m2 and maximum power density of 0.46 mW/m2 from body heat （temperature of 36℃）. For practical use, we have shown that the thermocell charges up a capacitor when worn on a T-shirt by a person. We also have demonstrated that the electrical energy generated from waste pipe heat using a serial array of the thermocells and voltage converters can power a typical commercial light emitting diode （LED）.

关键词： wearable thermocell body heat waste heat recovery carbon nanotubes activated carbon textile porous electrode

Effects of working parameters on gasoline engine exergy balance

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Journal of Central South University 2013年第7期20卷 1938-1946页

作者： LIU Jing-ping FU Jian-qin FENG Ren-hua ZHU Guo-hui Research Center for Advanced Powertrain Technology Hunan University Changsha 410082 China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body (Hunan University) Changsha 410082 China

To improve the energy utilization efficiency of internal combustion （IC） engine, exergy analysis was conducted on a passenger car gasoline engine. According to the thermodynamic theory of IC engine, in-cylinder exergy balance model was built. The working processes of gasoline engine were simulated by using the GT-power. In this way, the required parameters were calculated and then gasoline engine exergy balance was obtained by programming on computer. On this basis, the influences of various parameters on exergy balance were analyzed. Results show that, the proportions of various forms of exergy in gasoline engine from high to low are irreversible loss, effective work, exhaust gas exergy and heat transfer exergy. Effective exergy proportion fluctuates with cylinder volumetric efficiency at full load, while it always increases with break mean effective pressure （BMEP） at part load. Exhaust gas exergy proportion is more sensitive to speed, and it increases with speed increasing except at the highest speed. The lower proportion of heat transfer exergy appears at high speed and high load. Irreversible loss is mainly influenced by load. At part load, higher BMEP results in lower proportion of irreversible loss; at full load, the proportion of irreversible loss changes little except at the highest speed.

关键词： gasoline engine exergy balance waste heat recovery thermal efficiency energy conservation