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A Novel Technology for Generation of Electricity and Cold by Using Energy Potential of Transmission Line＇s High Pressure Gas

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Journal of Energy and Power Engineering 2015年第10期9卷 852-859页

作者： Zohrab Melikyan hvac department National University of Architecture and Construction of Armenia Yerevan 0009 Armenia

The main objective of this paper is to develop a novel technology for combined generation of electricity and cold by using energy potential of transmission line＇s high pressure gas. For this purpose, the reduction of high pressure of the gas in gas distribution station instead of useless expansion throttling process is suggested to realize by adiabatic expansion, which is executed in a gas expanding turbine. Herewith, the gas distribution station is turned into energy and cold generating plant. Simultaneous operation of energy and cold generating plant is described. A method and appropriate formulas for determination of design characteristics of considered plant are suggested. A new method for reveres order of calculation and design of the cold store based on the use of expanded cold gas as cooling agent is developed. Calculations and analysis prove high energy efficiency of suggested technology, the wide use of which will provide significant production of cheap electricity and cold and as well as reduction of fossil fuel consumption.

关键词： Natural gas gas distribution station throttling valve turbo-expander isenthalpic adiabatic.

Analysis of internal Heat Exchanger for Heat Pump System Using CO2

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Analysis of internal Heat Exchanger for Heat Pump System Usi...

Effect of the Mixing Structure Parameters of a Self-reflux Burner on Combustion Characteristics and NO_(x)Emission

第二届亚洲制冷空调大会

作者： Ook Joong Kim Yoo Yil Kim Yong Ju Hong Kong Hoon Lee hvac & Cryogenic Group Thermo-Fluid System Department 171 Jang-Dong Yusong-Gu Daejon 305-343 Korea

Analysis of internal heat exchanger for a CO heat pump system was performed using a finite elementapproach. Appropriate heat transfer correlation equations and the number of finite elements were determinedby comparing the calculation results with the experiment results from previous research. An internal heatexchanger using three tubes welded each other was suggested and designed. The performance characteristicssuch as heat transfer rate, effectiveness and pressure drop according to the variations of design parameters andoperating conditions were investigated. Not only operation conditions such as mass flow rate and inletpressure but also design parameters such as tube length, tube material and contact resistance can affect theinternal heat exchanger performance. Arrangement of tubes, counter or parallel, also brings significantperformance difference at the same operation condition.

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Journal of Thermal Science 2021年第4期30卷 1224-1236页

作者： XU Qian SHEN Meng SHI Kejian LIU Zhihui AKKURT Nevzat XIONG Yaxuan LIU Lin FENG Junxiao WANG Jiulong School of energy and environmental engineering Shunde Graduate SchoolUniversity of Science and Technology BeijingBeijing 100083China Beijing Key Laboratory of Energy Conservation and Emission Reduction for Metallurgical Industry Beijing 100083China department of Mechanical Engineering Munzur UniversityTunceli 62000Turkey Key Laboratory of hvac Beijing University of Civil Engineering and ArchitectureBeijing 100044China School of Mathematics and Physics University of Science and Technology BeijingBeijing 100083China department of Big Data Technology and Application Development Computer Network Information CenterChinese Academy of SciencesBeijing 100190China

To solve the problem of low efficiency of NO_(x)emission reduction in self-reflux burners,this study is based on the concept of coordinated control of self-reflux burner structural and thermal *** completing the structural design and optimization of thermal parameters,we continue to adjust the two key structural parameters:the nozzle axis distance and the length of the cylindrical section,to minimize NO_(x)*** are the two parameters that chiefly affect the mixing of flue gas and fuel *** results show that increasing nozzle axis distance can delay the mixing of gas and air and create a more uniform oxygen concentration field for the combustion *** maximum combustion temperature is reduced from 1973.65 K to 1935.88 K and the volume fraction of NO_(x)in the flue gas is reduced from 188.08×10^(–6)to 143.47×10^(–6).However,compared with the nozzle axis distance,the length of the cylindrical section of the burner has little effect on the mixing of the flow *** different cylindrical section lengths,the maximum combustion temperature does not change more than 3 K,and the volume fraction of NO_(x)in the flue gas changes within 5×10~(–6).

关键词： self-reflux structure structural parameter control thermal parameter combustion characteristic NO_(x)emission

Experimental and numerical investigation of gas diffusion under an urban underground construction

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Energy and Built Environment 2021年第4期2卷 436-444页

作者： Kang Zhou Fei Li Hao Cai Yibin Yang Fusheng Peng Li Chen Junyi Zhuang department of hvac College of Urban ConstructionNanjing Tech UniversityNanjing 210009P R China Engineering Research Center of Safety and Protection of Explosion&Impact of Ministry of Education Southeast UniversityNanjing 211189P R China College of National Defense Engineering Army Engineering UniversityNanjing 210007P R China PLA Unit 96784 LuoyangHenan 471399P R China

Rapid increase of urban underground constructions has a great consideration of underground environment safety and how to expel toxic gasses out of tunnels *** utility tunnel is a typical urban tunnel construction with multiple underground pipelines including gas pipelines,and it is necessary to investigate characteristic of gas diffusion and monitor gas leakage to ensure tunnel *** this study,the experimental measurements of airflow and gas distributions were conducted in a 10 m full-scaled utility tunnel mockup,and gas diffusion characteristic was also *** simulation of utility tunnel leakage was also conducted by computational fluid dynamics(CFD).Different turbulence models and different air supply diffuser models were compared via the experimental results based on visualization and the relative root-mean-square error(RRMSE)index,which quan-titated the difference between the numerical and experimental *** results showed that the standard k−εturbulence model and random air opening model could provide better results than other *** to the experimental data analysis,it was necessary to consider the optimization of monitoring detector arrangements in actual utility *** study provided basic experimental data and the validated numerical model for the leakage source identification and underground tunnels simulation research.

关键词： Urban tunnel Gas leakage Gas dispersion CFD Turbulence model Air supply diffuser

Synthesis and Characterization of Disodium Hydrogen Phosphate Dodecahydrate-Lauric-Palmitic Acid Used for Indoor Energy Storage Floor Units

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Journal of Thermal Science 2020年第2期29卷 477-485页

作者： XU Qian AKKURT Nevzat ZOU Zhenwei LIU Yang FENG Junxiao YU Chuqiao DING Chong XIONG Yaxuan ZHOU Jingzhi ZANG Yong DING Yulong School of Energy and Environmental Engineering University of Science and Technology BeijingBeijing 100083China department of Mechanical Engineering Munzur UniversityTunceli 62000Turkey School of Information and Electronics Communication and Information SystemBeijing Institute of TechnologyBeijing 100081China School of Mathematics Taiyuan University of TechnologyTaiyuan 030024China Key Laboratory of hvac Beijing University of Civil Engineering and ArchitectureBeijing 100044China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China School of Mechanical Engineering University of Science and Technology BeijingBeijing 100083China

Organic and inorganic phase change materials(PCMs) are considered potential materials for thermal energy storage(TES) with different phase change characteristics. In this study, a novel organic-inorganic composite phase change material(PCM) called disodium hydrogen phosphate dodecahydrate-lauric-palmitic acid(D-LA-PACM) was prepared. Expanded graphite(EG) was selected as the support material, and the novel organic-inorganic form-stable PCM called D-LA-PAPCM/EG was prepared using the vacuum adsorption method. Differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction, leakage testing, melting and solidification cycle testing, thermal conductivity testing, scanning electron microscopy observation of the micromorphology, and other characterization methods were used to study the microstructure and morphology, thermal physical parameters, thermal conductivity, stability of the PCMs, and the comprehensive material properties of D-LA-PAPCM under the composite action of EG. Results indicated that the melting and freezing temperatures and latent heats of D-LA-PAPCM/EG were measured to be 31.6℃ and 34.3℃ and 142.9 and 142.8 J/g, respectively. Although some of the lauric-palmitic acid(LA-PA) and disodium hydrogen phosphate dodecahydrate(DHPD) separated in the multiple porous structures of EG after 1000 cycles, they could still absorb and release latent heats independently, with D-LA-PAPCM/EG still exhibiting good thermal stability. The thermal conductivity of D-LA-PAPCM/EG was 1.361 W/(m·K). Therefore, the material and thermal properties of the prepared D-LA-PAPCM/EG indicate that it could be well used as a feasible material for energy-saving phase change floor units in indoor TES systems.

关键词： organic-inorganic PCM form-stable PCM thermal property energy storage

Data mining algorithm and framework for identifying hvac control strategies in large commercial buildings

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Building Simulation 2021年第1期14卷 63-74页

作者： Zhe Chen Peng Xu Fan Feng Yifan Qiao Wei Luo department of Mechanical and Energy Engineering Tongji UniversityShanghai201804China department of Mechanical Engineering The University of AlabamaTuscaloosaAL35487USA

Heating,Ventilation,and Air-Conditioning(hvac)control strategies are set arbitrarily in many commercial buildings by operators,who sometimes lack relevant skills and professional *** is acknowledged that improving the control strategy of hvac is feasible and valid,which as a consequence can improve the overall hvac performance of existing ***,it is quite difficult for an outsiders or a commissioning agent to tell what the hvac control strategies are and whether they are implemented appropriately in existing *** paper is intended to carry out analysis on the data about Building Automation System(BAS),as well as the data about building energy,for the purpose of identifying the control strategies of hvac in a given building by using data mining *** the results can be adopted by us to determine whether the building is under faulty operation or is running under suboptimal *** this paper,what are proposed are algorithms of data mining identification for some specific hvac control strategies,including DR on/off strategy,DR reset strategy and temperature reset strategy of chilled *** the basis of data mining algorithms,a framework is then developed so as to identify these strategies,and the main scenario of this identification framework is known as analyzing many commercial buildings on an energy monitoring platform of a public *** framework takes the sensor data obtained from hvac,including temperature,flowrate,and electricity usage,as input,which is followed by the application of Image Segmentation and PCA algorithm for ***,based on these input variables,XGBoost algorithm is employed to determine whether these strategies have been implemented in buildings or *** order to get the data for training and testing the framework,EnergyPlus Runtime Language is adopted for the application of different strategies.t is finally shown by the result that the identification algorithm can achieve the a

关键词： hvac control strategy identification data mining

Frost prediction based on a 3D CFD model of heat and mass transfer in a counter-cross-flow parallel-plate liquid-to-air membrane energy exchanger

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Building Simulation 2023年第11期16卷 2063-2076页

作者： Mohammad Alipour Shotlou Nader Pourmahmoud Mechanical Engineering department Urmia UniversityUrmiaIran

The frosting is a critical phenomenon in building systems because it decreases the performance of exchangers and damages *** this article,heat and mass transfer in a specified liquid-to-air membrane energy exchanger(LAMEE)and their effects on condensation and frost formation are simulated numerically using the 3D computational fluid dynamics(CFD)*** CFD model has been validated with experimental results for different design parameters,and the agreement is within±2%.The developed CFD model provides the distribution of temperature and humidity ratio and MgCh concentration along the *** the present study,effects of exchanger structure on producing viscosity and heat and mass transfer are *** selected LAMEE is a counter cross structure,therefore vortices appear in the inlet and outlet solution channel,and their influence can be seen on heat transfer in these *** addition,the diffusion of heat and mass transfer are studied on distributions of temperature and humidity *** show that the permeable membrane and moisture transfer make more regular temperature distribution along airflow direction in energy *** study provides an extended vision of heat and mass transfer.A 3-dimensional CFD model is developed to predict frost formation based on obtained temperature and humidity *** CFD model is validated with an experimental study by calculating the frost *** developed model distinguishes condensed and frosted areas,and a new parameter is defined for this purpose namely as the frosted humidity *** show that frost and condensation distributions depend significantly on temperature and humidity ratio *** temperature and humidity ratio to avoid air vapor to reach to saturation conditions is the better way to combat frosting.

关键词： frost CFD simulation moisture transfer membrane hvac LAMEE

New Optimization Method, the Algorithms of Changes, for Heat Exchanger Design

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Chinese Journal of Mechanical Engineering 2012年第1期25卷 55-62页

作者： TAM Houkuan TAM Lapmou TAM Sikchung CHIO Chouhei GHAJAR Afshin J department of Electromechanical Engineering Faculty of Science and TechnologyUniversity of Macao department of Mathematics Faculty of Science and TechnologyUniversity of Macao School of Mechanical and Aerospace Engineering Oklahoma State University

Heat exchangers are widely used in the process engineering such as the chemical industries, the petroleum industries, and the hvac applications etc. An optimally designed heat exchanger cannot only help the optimization of the equipment size but also the reduction of the power consumption. In this paper, a new optimization approach called algorithms of changes (AOC) is proposed for design and optimization of the shell-tube heat exchanger. This new optimization technique is developed based on the concept of the book of changes (I Ching) which is one of the oldest Chinese classic texts. In AOC, the hexagram operations in I Ching are generalized to binary string case and an iterative process, which imitates the I Ching inference, is defined. Before applying the AOC to the heat exchanger design problem, the new optimization method is examined by the benchmark optimization problems such as the global optimization test functions and the travelling salesman problem (TSP). Based on the TSP results, the AOC is shown to be superior to the genetic algorithms (GA). The AOC is then used in the optimal design of heat exchanger. The shell inside diameter, tube outside diameter, and baffles spacing are treated as the design (or optimized) variables. The cost of the heat exchanger is arranged as the objective function. For the heat exchanger design problem, the results show that the AOC is comparable to the GA method. Both methods can find the optimal solution in a short period of time.

关键词： optimization genetic algorithms (GA) travelling salesman problem (TSP) heat exchanger design algorithms of changes (AOC)

From occupants to occupants:A review of the occupant information understanding for building hvac occupant-centric control

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Building Simulation 2022年第6期15卷 913-932页

作者： Tao Yang Arkasama Bandyopadhyay Zheng O’Neill Jin Wen Bing Dong mike walker’66 department of mechanical engineering texas a&m universitycollege stationtx77843usa department of civil architectural&environmental engineeringdrexel universityphiladelphiapa19104usa department of mechanical and aerospace engineering syracuse universitysyracuseny13244usa

Occupants are the core of the built *** heating,ventilation,and air-conditioning(hvac)systems operate with predefined schedules and maximum occupancy assumptions with no consideration of specific occupant *** generalized assumptions usually do not align with the actual demand and result in over-conditioning and occupant *** recent years,with the aid of Information&Communication Technology(ICT)and Computer Science(CS),it is possible to acquire real-time and accurate occupant information to satisfy the exact thermal requirement through specific hvac control in one particular built *** mechanism is called hvac“Occupant-centric Control(OCC).”hvac OCC strategy starts with collecting the occupant’s information(e.g.,presence/absence)and then applies it to meet the occupant’s requirement(e.g.,thermal comfort).However,even though some research studies and field pilot demonstrations have been devoted to the field of OCC,there is a lack of systematic knowledge about occupant data,which is the principal component of OCC for hvac researchers and *** fill this gap,this review paper discusses OCC with a particular emphasis on occupant information and investigates how this information can assist hvac operation in providing an acceptable built environment in required spaces during the required *** provide a fine-grained,comprehensive picture of occupant information,discuss its features,the modalities of information feed-in into the hvac control,and the application of commonly utilized occupant information for OCC.

关键词： occupant information occupant-centric control smart building hvac energy efficiency