最新刊期
卷 28 ， 期 2 ， 2007
- 摘要：A hypobaric storage system controls the O2 concentration by regulating the atmospheric pressure,but its technology and effect differ from CA entirely.At a low pressure the CO2,C2H4,and volatile contaminant concentrations present in the incoming air decrease by up to 99% when the air expands during entry into the vacuum storage chamber,and increased gaseous diffusion and respiratory inhibition cause different commodity types to tolerate 0.1%-0.2% O2.Increased gaseous diffusion also promotes the escape of CO2,NH3 and C2H4 from within the commodity,while continuous air-changes flush these gases from the storage chamber.During ultra-low pressure hypobaric storage at 1.33-2.67 kPa a high relative humidity and the prevention of convective and radiant heat uptake by the commodity limit its water loss to the amount that can be evaporated in response to the small amount of respiratory heat it produces.O2 is so scarce that a horticultural commodity's respiratory heat production and ability to transfer heat by convection are inhibited by 90%,An ultra-low pressure prevents bacterial and mold growth,kills insects,prevents CO2-damage,inhibits ethylene production by >90%,inhibits toxic succinate formation,limits ascorbic acid loss,and inactivates ethylene forming enzyme.Therefore,the hypobaric equipment is the most beneficial for horticultural commodity storage.The paper will summarize hypobaric research results and the development of LP systems in the West,and evaluate important differences between hypobaric research in China and the West.关键词：Food package and storage;Low- pressure storage;Heat- transfer;Water- loss;Insect- quarantine;Respiration;Ethylene1741|331|0更新时间：2025-09-03
- 摘要：The "effective region" of multi-connected air-conditioner(heat pump) system was proposed,which includes the safety region,the efficiency region and the adjustability region.Based on the system simulation model,the factors that influence the three effective regions were investigated.Moreover,the quantitative regions are presented for the system charged with HCFC22.1697|337|0更新时间：2025-09-03
- 摘要：The effects of space of fins, number of tube rows and relative humidity of incoming air on airside performance of waw fin with hydrophilic coating under dehumidifying conditions were experimentally explored for seven waw fin - and - tube heat exchangers with hydrophilic coating. The Colburn factor and the Fanning friction were applied to describe airside heat transfer and friction characteristics, respectively. The test results indicate that the Colburn factor and the friction factor increase with the decrease of space of fins. The Colburn factor decreases when number of tube rows increases while the effect of number of tube rows on the friction factor is small. When inlet relative hu- midity increases, the Colbum factor increases and the friction factor almost remains unchanged. Inlet relative humidity has a more significant effect on the Colburn factor when the inlet water temperature is lower.关键词：pyrology;Airside performance;Experimental;Waw fin;Dehumidifying conditions;Hydrophilic coating1639|348|0更新时间：2025-09-03
- 关键词：pyrology;display cabinet;Internal located refrigeration unit;performance;Ambient temperature and relative humidity1691|333|0更新时间：2025-09-03
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- 摘要：A brief review of two-phase cooling applications was presented.The differences between MPLHP(Mechanical Pumped Loop Heat Pipe) and LHP/CPL(Loop Heat Pipe /Capillary Pumped Loop)or Mechanical Pumped Single-phase Cooling Loop were discussed according to working mechanism and heat transfer characters.The characters of MPLHP system using CO2 as a working fluid were investigated theoretically and experimentally.The results show that the loop heat pipe driven by a mechanical pump has obvious advantages,such as lower power consumption,higher control accuracy,and compactness.关键词：Power machinery and engineering;Mechanical Pumped Loop Heat Pipe;Two- phase;Space;cooling1669|346|0更新时间：2025-09-03
- 摘要：A low - temperature test system was set up to investigate temperature characteristic of electronic expansion valves on low - temperature devices. In the system, a thermostatic expansion valve and an electronic expansion valve were installed in parallel. The experimental results show that the temperature control curves are smooth and steady with the electronic expansion valve at the low - temperature conditions. In addition, different temperature drop rates and final balanced temperatures can be achieved by changing the open degree of the electronic expansion valve.关键词：pyrology;electronic expansion valve;Throttling device;Temperature characteristic;Low- temperature device1500|348|0更新时间：2025-09-03
- 摘要：The feasibility of air cycle heat pump dry technology was analyzed. A simple theoretical model was set up and the energy efficiency of ventilation heating dry technology was compared with that of air cycle heat pump dry technology. Mathematic models for all thermodynamic parts were set up using integrate performance coefficients and their thermodynamic relations. The experiment and simulation results show that the energy efficiency of air cycle heat pump dry technology is greatly higher than that of the ventilation heating dry technology.关键词：pyrology;Air cycle heat pump;Dry technology;Energy efficiency1573|339|0更新时间：2025-09-03
- 摘要：A new double - capillary tube refrigeration system for refrigerator - freezers was proposed. A capillary tube was added between the two evaporators in the fresh and frozen food storage chests to raise the evaporation temperature of the fresh food, and reduce the heat exchange temperature difference and the available energy loss. PR equation was adopted to calculate the thermodynamic properties of the refrigerants, and the available energy analysis for the vapor compression refrigeration cycle was programmed to calculate thermodynamic performances of the new and the conventional refrigeration cycle of therefrigerator - freezer. The calculation results show that the available energy efficiency of the conventional refrigeration cycle of the refrigerator - freezer is 21.20% and 20.57%, respectively when the refrigerant is R12 and R134a while that of the double - capillary tube refrigeration cycle of the refrigerator - freezer is 23.97%and 23.44%, respectively. By comparison, the available energy efficiency of the new refrigeration system increases by 13.07% and 13.95%, respectively.关键词：pyrology;Double - capillary tube;Available energy analysis;Chest refrigerator1679|345|0更新时间：2025-09-03
- 摘要：The performances of energy separation in a vortex tube were experimentally studied with compressed air to be the working medium and the influences of inlet pressure and cold mass flow fraction on cooling effect and heating effect of the vortex tube were obtafned. The results show that the cooling effect and the heating effect of the vortex tube with the nozzle of six flow passage increase with the increase of the inlet pressure, and the cold mass flow fraction decreases at the biggest cooling effect and heating effect.关键词：pyrology;vortex tube;Energy separation;Nozzle;Temperature effect1633|333|0更新时间：2025-09-03
- 摘要：The simulation on an evaporator of an R134a air-conditioning unit was conducted with a steady state distribution parameter model.Using the update Kattan model,R134a flow patterns inside smooth tubes were divided, and then the flow pattern map was obtained.Based on the flow pattern map,local boiling heat transfer coefficients were calculated with different correlations.The surface heat transfer coefficient and the pressure drop of louver fin evaporators were calculated with C C Wang's model.The moisture separation coefficient was determined from the database established with test data.During simulation,implicit cubic polynomial curve-fitting model was used to calculate R134a thermodynamic properties.The results show that the simulation values are in agreement with the experiment data.The average relative error of refrigeration capacity,dry bulb temperature of outlet air,and R134a outlet temperature is 1.12%,1.25%,and 4.0%,respectively.Moreover,the maximum relative error of outlet-air enthalpy is 0.88%.关键词：pyrology;evaporator;Steady state distribution parameter model;Experiment1714|350|0更新时间：2025-09-03
- 摘要：A theoretical analysis was carried out and a mathematical model was proposed for air - cooler frosting performance. The comparison of the calculated thickness Of the frost layer shows good agreement with the experimental data. The average difference is 8.99%. Further studies were carried out on the factors affecting heat transfer surface, the coefficient of heat transfer and the air side pressure drop during a frosting process. The characteristics of frost growth were analyzed under different inlet air temperature, relative humidity and velocity. The calculated results show that the inlet air temperature and the relative humidity of the inlet air have obvious influence on the frosting. Disadvantages of the present defrosting methods were analyzed. In order to reduce the first cost and energy consumption of the refrigeration system for a cold - storage enterprise, an improved method of defrosting for an ammonia air - cooler was proposed. It was proved that the improved method is practical for improving the energy saving, lowering manufacture cost and enhancing economical benefits.关键词：engineering thermophysics;Air - cooler;Frosting performance;Frosting rate;defrosting;energy saving1653|318|0更新时间：2025-09-03
- 关键词：Food package and storage;Vacuum freeze drying;Technological parameter;power consumption1592|338|0更新时间：2025-09-03
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