查看更多>>摘要：The paper focus on developing hydrogen storage systems for ship's fuel cell power units。 Activated carbon SAC03， MIL-101 and its composite JMU-01 formed by mixing the expanded natural graphite (ENG) in 10 wt% were selected。 Adsorption data of hydrogen were measured at a temperature range 77。15 K-87。15 K within pressure 0-6 MPa。 Accuracies of results predicted by Toth and Dubinin-Astakhov (DA) equations were evaluated， the isosteric heat of adsorption and the interaction potential were then determined。 A conformable vessel that can meet the fuel consumption required by 7。5 kW PEMFC was employed charge and discharge tests at ambient temperature and 77。15 K。 Results show that， the isosteric heats of hydrogen adsorption on the SAC-03， MIL-101 and JMU-01 are 4。09 kJ center dot mol- 1-1。43 kJ center dot mol-1， 4。20 kJ center dot mol- 1-1。89 kJ center dot mol-1 and 4。19 kJ center dot mol- 1-2。20 kJ center dot mol-1， interaction potential between hydrogen molecules and SAC-03 and MIL-101 are 32。48 K center dot k and 41。09 K center dot k。 Results also reveal that the desorption ratio (DR) of SAC-03， MIL-101 and JMU-01 at ambient/77。15 K temperature are respectively 0。83/0。85， 0。74/0。81， 0。85/0。85， and the mean usable capacity ratio (UCR) is respective about 6。55/1。36， 6。08/1。32， 6。02/1。31。 It suggests that addition of ENG is beneficial to improving the DR of the adsorbent but has a negative effect on the UCR of the storage vessel， and cryo-adsorption of hydrogen on MOFs is more promising than activated carbons。
查看更多>>摘要：A superconducting liquid helium level sensor has been used as a temperature sensor to monitor cooldown and warmup of the holding device。 Temperature dependent resistance of NbTi wire is utilised for measuring surrounding gas space temperature (300 K-5 K) during the transition time。 Theoretical calculation for the system revealed that during passage of current， temperature rise of the wire will be restricted to safe limits due to generation of high natural convection gas flow around the sensor， initiated by the its heating。 Actionable decisions can be started based on this measurement for controlling cooldown and warm up process of the system。 Depending on helium temperature， a dual use electronics meter has been proposed which can measure either gas temperature or liquid helium level using the same sensor。 Utilising this principle any existing LHe level sensor can also be operated as a temperature sensor during thermal transition process。
查看更多>>摘要：An extruder-type cryogenic pellet injector system for plasma fuelling is under research at Institute for Plasma Research (IPR)， India。 A twin-screw extruder is a most stable device in the form of closed volumes of hydrogen between screw threads and promising process due to continuous production of hydrogen pellet for plasma reactor。 In the present investigation， a non-Newtonian， non-isothermal CFD model was developed which modeled the shear rate and temperature-dependent viscosity in the Herschel Bulkley model。 Brinkman number (Br) varies from 0。15 to 0。46 at 5 and 15 rpm respectively。 Due to increasing the screw rotation speed for a given throughput， the shear rate increases (therefore， also the Br) and results in larger viscous dissipation。 Solid hydrogen temperature is predicted at the location of the flight gap and intermeshing zone for the different barrel temperatures under varying screw rotation speeds (5-15 rpm)。 Prediction of hydrogen temperature at the intermeshing zone of the extruder system plays a vital role to decide the barrel temperature。 Due to more number of moving surfaces at the intermeshing zone of the extruder system， the temperature of solid hydrogen is higher and increases above the melting point temperature。 The effect of barrel wall temperature and screw rotation speeds (5-15 rpm) on the viscous dissipation rate and pressure development at required throughput was also examined for an extruder system。 It is important to estimate the barrel wall temperature to get an operating point and corresponding viscous dissipation rate， which determines the cooling load required for extruder-die set-up。 The results show that as the die wall temperature increases， the viscous dissipation， as well as the pressure drop decreases in the die。 The investigation showed that the die's wall temperature and screw rotation speed affect the operating point of the extruder-die system。
查看更多>>摘要：Printed circuit heat exchanger (PCHE) is a compact plate heat exchanger that etches microchannels on plates by chemical etching method and exploits bonding force between the atoms to achieve diffusion bonding。 It has the promising applications in the fields of floating liquefied natural gas， nuclear reactor， hydrogen energy， etc。 The influence of structural parameters on flow and heat transfer characteristics in a Zigzag-channel PCHE was investigated using supercritical methane as flow media。 Three-dimensional turbulent steady numerical method was determined and verified through the SST k- omega turbulent model in FLUENT platform。 The influence mechanism of structural parameters on flow and heat transfer characteristics was analyzed from temperature distribution， turbulent dissipation rate， vortex vector， turbulent intensity and helicity。 The results indicated that the worse flow and better heat transfer performance exhibited under the condition with small channel diameter， small pitch and large bending angle。 Meanwhile， the optimization analysis was also conducted though the coupling consideration of flow and heat transfer performances of PCHE using thermal performance factor (TPF)。 The optimum channel was obtained with the diameter， channel pitch， and bending angle of 1。427 mm， 24。6 mm， and 15 degrees respectively， in scope of this study。 The optimum structure parameters obtained herein will be instructive in the design of PCHE。
NSTL
Elsevier