ENGINEERING NEWS IN BRIEF

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                  ENGINEERING NEWS IN BRIEF
                        E-Mail Newsletter

                               No.69
             Issued by the Asian TOP Panel, September2007

           The Chinese Mechanical Engineering Society (CMES)
           The Institution of Engineers, Indonesia (PII)
           The Japan Society of Mechanical Engineers (JSME)
           The Korean Society of Mechanical Engineers (KSME)

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    According to the agreement made in the 2nd Asian TOP Panel Meeting,
the ENGINEERING NEWS IN BRIEF (E-mail newsletter) has now been edited
by the CMES for the year 2007.

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[Contents]

(1) Running Characteristics of Adsorption Cooling Tube Air-Conditioner Powered by      Waste Heat of Engineering Trucks (Source: CMES)
(2) Non-Uniform Difussion Vane Assembly in CHEMICAL Axial Pump (Source: CMES)
(3) Heat-Transfer Character Analysis of Rings of Mechanical Seal (Source: CMES)
(4) A Research of an On-Board Heat Waste Recovery System - A Challenge by
     Using the Rankine Cycle - (Source: JSME)
(5) Energy Supply System with Functions of Both Generation and Storage of
     Hydrogen Gas for Commercial Buildings (Source: JSME)
(6)'Green' Composites -Biomass Derived Materials That Promote A
     Recycling-Oriented Society - (Source: JSME)
(7) Mechanical Characterization of Elastomeric Polymer through Micro Instrumented      Indentation Technique (Source: KSME)
(8) Shape Optimization of a Micro-Channel Using Kriging Model (Source: KSME)
(9) Natural Convection Heat Transfer from a Heated Fine Wire in Nanofluids
     (Source: KSME)

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(1)Running Characteristics of Adsorption Cooling Tube Air-Conditioner Powered by     Waste Heat of Engineering Trucks

    WU Weidong ZHANG Hua
    College of Power Engineering, University of Shanghai for Science & Technology

An adsorption cooling tube knockdown air condi- tioning system powered by waste heat of engineering trucks is designed and manufactured. The relevant theoretical models and performance analysis indexes are presented. Then running performance experiments and relevant analysis for the air conditioning system are carried out. Under the conditions of a certain outside environment and 30 min of half cycle time, the maximum refrigerating temperature fall extent of cooled air is 13.0 ℃, the maximum cooling power is 1.10 kW, the mean cooling power of the system is 842 W, the coefficient of per- formance e c is 0.168, the specific cooling power Ps is 88.2 W/kg, when air is used as the cooling medium for the adsorber of air conditioner. The maximum refrigerating temperature fall extent of cooled air is increased to 14.0 ℃, the maximum cooling power, the mean cooling power of the system, e c and Ps are up to 1.21 kW, 926 W, 0.177 and 97.0 W/kg, respectively, when an improved cooling way for the adsorber of air conditioner is used. The conclusions can be drawn that the increased extent of e c is about 5.4%, and the increased extent of the maximum cooling power, the mean cooling power or Ps is near 10% respectively.

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(2)Non-Uniform Difussion Vane Assembly in CHEMICAL Axial Pump

    LIANG Kaihong CAO
    Shuliang Department of Thermal Engineering, Tsinghua University,
    ZHANG Kewei
    Institute of Energy and Power, Huazhong University of Science and Technology

Usually chemical axial pump doesn't mount diffusion vane because the distance between impeller and elbow is too short. But this manner would waste energy greatly because the kinetic energy associated with circular velocity at impeller outlet will dissipate gradually in flow passage. In order to increase the unit efficiency, computational fluid dynamics method is adopted to explore the internal flow characteristics for different diffusion vane assemblies. The mechanics is studied, which can explain why hydraulic performance becomes deteriorative when the normal diffusion vane is installed in chemical axial pump. Numerical simulation results indicate that the non-uniform diffusion vane assembly can optimize the unit hydraulic performance effectively.

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(3)Heat-Transfer Character Analysis of Rings of Mechanical Seal

    ZHOU Jianfeng, GU Boqin
    College of Mechanical and Power Engineering,Nanjing University of Technology

The transfer regularity of the frictional heating of the end faces of mechanical seal in the system consist of the rotating ring, the stationary ring, the fluid film in the end faces and the sealing medium is investigated. Taking the heat-transfer area as a constant, each ring can be simplified as an equivalent cylinder. The equations for calculating the frictional heat transferred by each ring are derived, and the temperature distribution in seal rings is discussed. The frictional heat increases both with the increase of the rotational speed and with the decrease of the average film thickness. Because the most frictional heat is transferred by the rotating ring into the sealing medium, the temperature change of the stationary ring is relatively small. For the rotating ring, the temperature beside the air is higher than that beside the sealing medium. The end face of the rotating ring processes the highest temperature and there exists radial temperature gradient. It is possible to reduce the highest temperature and the temperature difference between the inner diameter and the outer diameter by increasing the heat-transfer area or using the material with higher coefficient of heat conductivity in order to improve the performance of mechanical seals.

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(4) A Research of an On-Board Heat Waste Recovery System - A Challenge by
     Using the Rankine Cycle -

     Shogo KAWAJIRI, Honda Motor Co.,Ltd
     Toshihiro TSUTSUI, Honda Motor Co.,Ltd

Several systems to salvage the waste energy from the vehicle engine are developing. Recently the Staring engine, the thermoelectric element and so on are studied hardly to improve the engine efficiency. However, it has not be carried out these systems to be enough light and compact boarding no the commercial vehicle.
We Honda have a mission to save the discharge of CO2 gas from the vehicles. From this concept, we challenged to develop an on-board heat waste recovery system by using the Rankine cycle. This system needs a device to separate the lubricating oil from the water because it used pure water as a medium. Still more, in the real operation, it needed a control system to regulate the temperature and pressure of the medium automatically.
And in fact, when a prototype hybrid vehicle boarded this system is real running, we certified it could be transferred into the electrical energy from the waste one, and increased a 3.8 point in the thermal efficiency.

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(5) Energy Supply System with Functions of Both Generation and Storage of
     Hydrogen Gas for Commercial Buildings

     Hideyuki OKAMOTO,
     Research and Development Center, Takasago Thermal Engineering Co.,Ltd.

National Institute of Advanced Industrial Science and Technology and Takasago Thermal Engineering Co.,Ltd. jointly develop a new energy supply system for commercial buildings. This system consists of the unitized reversible cell stack(URC),that connects with both functions of the water electrolysis and the hydrogen fuel cell, and the metal hydride tank. The hydrogen gas generated from water electrolysis by using both electric power and natural energy that is solar, wind and etc. is stored into the metal hydride tank. After switching the operation-mode, we obtain the electric power generated from the hydrogen fuel cell by reacting with the hydrogen gas and oxygen gas(or air).Moreover, we obtain the cold water of ca.7℃ generated from the hydrogen gas storage tank during hydrogen gas supply, and the hot water of ca. 65℃ generated from the hydrogen fuel cell during operation. In this paper, we introduce the development situation of metal hydride tank and the 1kW-class URC as this main equipment.

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(6)'Green' Composites -Biomass Derived Materials That Promote A Recycling
     -Oriented Society -

Hitoshi TAKAGI, Institute of Technology and Science, The University of Tokushima

This paper deals with environment-friendly composite materials, i.e. 'green' composites, which are composed of biodegradable polymers and natural plant fibers. Except for the special case, it is possible for 'green' composites to use the same forming methods used for making the conventional glass-fiber reinforced plastics (GFRP). Furthermore, there is the merit of good abrasion resistance during molding, because natural fiber is softer than the glass fibers. However, natural fibers have marked poor thermal resistance compared with glass fiber, thus it is important to select an optimal forming temperature and other conditions. The mechanical properties of 'green' composites made from Manila hemp fibers and starch-based biodegradable resin are presented. The experimental results showed that this composite material possessed extremely high tensile strength of about 300 MPa. Finally the application of 'green' composites also presented. Recently, kenaf short fiber reinforced poly lactic acid (PLA) composites have been developed and applied to automobile interior parts and chassis materials for mobile phones.

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(7)Mechanical Characterization of Elastomeric Polymer through Micro Instrumented     Indentation Technique

    Gyujei Lee, Seungkyun Kang, Ingeun Kang, Dongil Kwon Seoul National University

In this study, the Johnson-Kendall-Roberts (JKR) theory was combined with the instrumented indentation technique (IIT) to evaluate work of adhesion and modulus of elastomeric polymer. Indentation test was used to obtain the load-displacement data for contacts between Tungsten Carbide indenter and elastomeric polymer. And the JKR contact model, contrived to take viscoelastic effects of polymer into account, was applied to compensate the contact area and the elastic modulus which Hertzian contact model would underestimate and overestimate, respectively. Besides, we could obtain the thermodynamic work of adhesion by considering the surface energy in this contact model. In order to define the relation between JKR contact area and applied load without optical measuring of contact area, we used the relation between applied load and contact stiffness by examining the correlation between JKR contact area and stiffness through dimensional analysis with 14 kinds of elastomeric polymer. From this work, it could be demonstrated that the interfacial work of adhesion and elastic modulus of compliant polymer can be obtained from a simple instrumented indentation testing without area measurement, and provided as the main algorithm of compliant polymer characterization.

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(8)Shape Optimization of a Micro-Channel Using Kriging Model

    Afzal Husain, Kwang-Yong Kim Inha University

Microchannel heat sink shape optimization is performed using Kriging method. Design variables relating to microchannel width, depth and fin width are selected, and thermal resistance has been taken as objective function. Design points are selected through a three-level fractional factorial design of sampling method. Navier-Stokes and energy equations for laminar flow and conjugate heat transfer are solved at these design points using a finite volume solver. Solutions are carefully validated with experimental results. Using the numerically evaluated objective function, a surrogate model (Kriging) is constructed and optimum point is searched by sequential quadratic programming. The process of shape optimization greatly improves the thermal performance of microchannel heat sink under constant pumping power.

Key words: Trapezoidal Microchannel, Optimization Technique, Surrogate Model, Kriging, Navier-Stokes Equation

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(9) Natural Convection Heat Transfer from a Heated Fine Wire in Nanofluids

     Shinpyo Lee Kyonggi University

Recent research on nanofluids under forced convection experiment shows that there is little relationship between convective heat transfer and thermal conductivity increase of nanofluids. This kind of new findings are totally different from the traditional theory of nanofluids, which says that the higher thermal conductivity is a prerequisite for convective heat transfer enhancement. To elucidate this controversial issue in a very comprehensible manner, simple natural convection experiment has been carried out for the water- and oil-based nanofluids. (water-Al?O?, transformer oil-Al?O?) Present research shows that there exists strong dependence between natural convection performance and thermal conductivity increase of nanofluids.

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Editor : Tian Ruizhu
           The Dept. of Internationa Affairs
           Chinese Mechanical Engineering Society