冻肉的解冻方法

国内目前通用的解冻法是空气解冻法和流水浸泡解冻法。     

解冻技术在肉制品中的应用研究进展

目的 对国内外肉品解冻技术的研究进展进行综述,以提高解冻效率和解冻肉的品质.方法 阐述各种解冻技术对肉制品的作用机理,分析其优势和限制其推广应用的关键问题;论述应用于牛肉、猪肉和羊肉的解冻工艺,并对肉品解冻的未来研究方向进行展望.结论 各种解冻技术均有利弊,对于牛肉,高压静电解冻技术虽是一种极具潜力的新型解冻技术,但仍存在解冻规模小和生产成本高等问题;对于猪肉,低温高湿解冻较适用于实际生产;对于羊肉,冷水和低温空气解冻是较为合适的方法.未来可根据不同肉制品的特性,有针对性地研究其解冻工艺.同时,也应对组合解冻技术和肉品的预处理技术进行研究,以提高冻肉的解冻效率和品质.     

速冻马铃薯在高压直流电场中解冻的实验研究

微能源在食品工业中的应用日益广泛。本文实验研究了不同场强对快速冻结马铃薯的解冻过程和解冻后质量的影响,主要考察解冻曲线、质地特性,液汁流失三方而。研究发现高压直流电场场强不同对马铃薯解冻过程的作用有差异：在150kv／m场强以下时延缓解冻,反之则会加速解冻进行;不同场强对马铃薯解冻前后的质地特性、液汁流失影响较小。     

150米~3/时制氧机热交换器单加温解冻

介绍“150”制氧机在高温季节热交换器经常堵塞,从经济角度出发,采用单加温解冻。具体做法有快速升温法、气体冲击法和缓解法。指出,当水分冻结多时,从高压阀中通入高压空气,直接与冻块换热,加快加热时间,可获得较好效果。     

高压静电对速冻冬枣解冻品质的影响

利用高压静电解冻的方法,研究不同解冻场强、解冻时间和解冻温度对速冻冬枣解冻品质的影响.结果表明:高压静电解冻效果优于自然解冻,高压静电解冻后,冬枣硬度、含水量、有机酸含量、维生素c含量和可溶性糖含量均维持较高水平,汁液流失较少.适宜的解冻时间和解冻环境温度对解冻冬枣品质也有一定影响,适宜的解冻条件为18℃、100kV/m下解冻40min.     

超声空化场速熔高分子化合物的现象及其机制

1　引　言超声喷泉的灼热现象导致了喷射超声空化场和空化集中概念的提出[1,2 ] 。本文作者还将这种物理新概念成功地应用于破穿冰块、解冻食品和促进苏铁种子萌发等实验中[3 5] 。进一步的研究还表明 ,从换能器辐射面开始 ,在向上喷射着的这种空化水(场 )的中轴线上均能引起灼热现象。本文报告了这种喷射超声空化场 (水 )速熔高分子化合物的现象 ,并提出了它的机制。1、压电陶瓷换能器 ;2、容器 ;3、自来水 ;4、超声喷泉 (即空化着的水 ,一种喷射超声空化场 ) ;5、试样 (有机玻璃 ,ＡＢＳ塑料等高分子化合物 )图 1　实验装置2　实　验实验…     

空分系统加温解冻方法的改进

本文介绍了“两步加温解冻法”——分别采用罗茨鼓风机加压干氮和透平空气对空分系统的低压和中压部分进行加温解冻,该方法弥补了单用罗茨鼓风机加压干氮或单用透平空气对整个中、低压空分系统加温解冻的一些欠缺:气量小、气压低、解冻时间长或易堵塞等。     

表冷器传热传质的数值模拟及特性研究

表冷器是集中式中央空调系统中的主要的空气处理部件。在系统仿真过程中,能否有效的模拟表冷器,是建立集中式中央空调系统数学模型的关键。本文基于表冷器的传热传质过程建立了其数学模型,并对模型进行了求解,得出了多工况下表冷器的稳态及动态特性。结果显示,该模型在进行稳态和动态仿真时,都具有良好的的效果。表冷器具有良好的空气处理能力,其空气的出口状态受空气的进口空气状态和冷水的进口状态联合决定,但是冷水的影响要比空气的影响迅速而且影响程度深。     

速冻马铃薯在高压直流电场中解冻的实验研究

微能源在食品工业中的应用日益广泛.本文实验研究了不同场强对快速冻结马铃薯的解冻过程和解冻后质量的影响,主要考察解冻曲线、质地特性,液汁流失三方面.研究发现高压直流电场场强不同对马铃薯解冻过程的作用有差异.在150kV/m场强以下时会延缓解冻,反之则会加速解冻进行;不同场强对马铃薯解冻前后的质地特性、液汁流失影响较小.     

不同解冻方式对金枪鱼肉品质的影响

目的 探究不同解冻方式(盐水解冻、水浴解冻、流水解冻、超声解冻、低温解冻)对金枪鱼品质的影响。方法 通过分析金枪鱼肉不同解冻方式的解冻时间、保水性(蒸煮损失率、解冻损失率、持水力)、pH、菌落总数、TVB-N和感官评定。结果 低温解冻的鱼肉有着较好的保水性和色泽,但是解冻时间最长。超声解冻和流水相较于其他解冻方式,解冻时间有着显著减少(P＜0.05)。其中超声解冻后鱼肉品质明显优于流水解冻后鱼肉品质,解冻后的鱼肉菌落总数(3.73 lg(CFU/g))和挥发性盐基氮含量(6.18 mg/100 g)显著低于流水解冻。结论 超声解冻是一种较好的金枪鱼肉解冻方式。     

间冷冰箱回风道的优化除霜设计

间冷冰箱蒸发器霜层分布对除霜加热器除霜热量分布的不一致性会导致除霜时间增加和除霜效率的降低,因此,本文提出一种间冷式冰箱回风道的优化除霜设计方法。首先通过实验测量除霜加热器表面温度分布,确定除霜加热器除霜热量分布,进而确定与除霜热量相匹配的蒸发器结霜分布;然后基于蒸发器结霜分布确定回风道出口的最优风量分布;最后基于最优的风量分布设计回风道,使蒸发器上霜层分布与除霜加热器除霜热量分布相一致,达到优化除霜的目的。通过某间冷冰箱回风道的优化设计案例表明,优化后的回风道可实现出口风量分布与除霜加热器除霜热量分布相匹配,除霜时间缩短了38.9%,同时使冰箱的制冷量增加了3.43%。     

空气源热泵结霜机理及除霜/抑霜技术研究进展

结霜导致蒸发器的热阻增加,传热系数降低,系统COP减小,制约了空气源热泵的推广应用。本文在表面结霜机理研究现状的基础上,总结了影响结霜的各种因素相应除霜/抑霜技术,综述了逆循环、热气旁通和电加热三种常用除霜方法的研究进展,概括了改变空气参数、表面温度和换热器结构的抑霜效果,以及表面改性抑霜技术的研究现状。指出霜导热系数模型的局限性及除霜/抑霜技术存在的问题,提出今后应结合多种措施着重探索对水蒸气凝结、冷凝水冻结、霜层回融和塌陷等阶段均有较强抑制作用的抑霜技术。     

Improving defrosting performance by controlling frost distribution to match defrosting heat distribution in frost-free household refrigerators

In the defrosting process of most of existing frost-free refrigerators, major part of the heat generated by electric heater cannot be absorbed by the frost, resulting in the raise of the energy consumption. The objective of this study is to present a new method to improve the energy efficiency in the defrosting process. Based on the idea of making the frost absorb most of the heat generated by electric heater, a new method of defrosting is proposed, and its principle is to make the defrosting process at different locations complete simultaneously by optimizing the frost mass distribution on the evaporator. In this method, the defrosting heat distribution on evaporator surface, the required frost mass distribution, the required air flow distribution and the structure of return air duct are determined, respectively. Application of this method in an actual household refrigerator shows that the defrosting efficiency is improved by 29.8%.     

Comparison of ultrasonic distillation to sparging of liquid mixtures

The application of intense ultrasound to a liquid-gas interface results in the formation of an ultrasonic fountain and generates both mist and vapor from the liquid. Here, the composition of the vapor and aerosol above an ultrasonic fountain is determined as a function of irradiation time and compared with the results of sparging for five different solutions. The experimental apparatus for determining the efficiency of separation consists of a glass vessel containing a piezoelectric transducer driven at either 1.65 or 2.40 MHz. Dry nitrogen is passed over the ultrasonic fountain to remove the vapor and aerosol. The composition of the liquid solutions are recorded as a function of irradiation time using gas chromatography, refractive index measurement, nuclear magnetic resonance, or spectrophotometry. Data are presented for ethanol-water and ethyl acetate-ethanol solutions, cobalt chloride in water, colloidal silica, and colloidal gold. The experiments show that ultrasonic distillation produces separations that are somewhat less complete than what is obtained using sparging.     

Field test study of a novel defrosting control method for air-source heat pumps by applying tube encircled photoelectric sensors

To improve the defrosting accuracy of air source heat pumps (ASHPs), this paper proposes a novel defrosting control method by applying tube encircled photoelectric sensors (TEPSs). A field test was conducted for two heating seasons in Beijing, China, to verify the feasibility and practicality of the novel TEPS method. The test results revealed that irrespective of the environmental conditions, the TEPS method can initiate defrosting in similar situations: most of the heat exchanger surface had been covered by frost; the compressor suction temperature decreased by ~9 °C; the compressor discharge temperature increased by ~16 °C; and the heating capacity decreased by ~30%. Furthermore, the TEPS method was verified to make more accurate and more reasonable defrosting decisions than the traditional T-T method under both frosting and non-frosting conditions. The results indicate that the TEPS method is a competitive defrosting control method that can be used for ASHPs.     

Experimental study of warm-air defrosting of heat-pump evaporators

The defrosting of a heat-pump evaporator with warm air has been investigated experimentally under controlled conditions in an air-conditioned wind tunnel. The work was initiated to explore the possibility of defrosting an evaporator under conditions where a heat pump continues to perform heating duty. A four-row straight-fin heat exchanger was used, supported from below by a load transducer to measure its weight variation during both frost accumulation and removal. The rate of melting was determined as a function of air temperature, relative humidity and velocity. The removal from the evaporator surfaces of water produced by defrosting was found to be dependent on air velocity. Proposals are advanced for further experimental studies.     

空气源热泵热水机组模糊除霜控制器的研究

设计空气源热泵热水机组模糊除霜控制方案,并从输入量模糊化模块、模糊推理模块、除霜控制模块、除霜监控、规则调整模块等方面对模糊除霜控制器进行深入研究,构建完善的控制流程,并进行实验研究,其结果表明该控制器有助于空气源热泵热水机组除霜性能的改进和提升,同时也提高了机组在低温、高湿工况下运行的稳定性和对环境的广泛适应性。     

A novel defrosting control method based on the degree of refrigerant superheat for air source heat pumps

When an air source heat pump (ASHP) unit operates for space heating at a frosting environment, periodic defrosting is necessary to maintain a high system performance. To defrost efficiently, it is necessary to find an effective defrosting control method. In this paper, an experiment was carried out on an ASHP unit with a capillary tube as a throttle device, under simulated frosting and defrosting conditions using time control defrosting method, and the experimental results are firstly presented. Secondly, a novel defrosting control method based on the degree of refrigerant superheat (DS) is reported. To validate the novel defrosting control method, a further experiment was conducted on another ASHP unit with an electronic expansion valve (EEV) as a throttle device, under simulated frosting and defrosting conditions. The experimental results demonstrated that when applying the novel defrosting control method, defrosting was initiated before the operating performances of ASHP unit rapidly deteriorated, which was more reasonable.     

空气源热泵蓄热系统形式及研究进展

蓄热技术与空气源热泵的结合可以提供空气源热泵除霜的热量来源,弥补空气源热泵制热量随着室外空气参数变化的波动,解决供需矛盾,并起到电力的移峰填谷作用。本文综述了蓄热技术在空气源热泵中的应用范围,介绍了空气源热泵的蓄热除霜系统,空气源热泵在供热调节和电力调峰方面的作用,以及作为热泵热水器在供热水方面的应用,认为未来空气源热泵蓄热系统将在除霜、供热、热水器以及电力调峰方面发挥更大的作用,指出对于蓄热材料的选择和用量、蓄热罐的选型和容积等问题是未来的研究方向。