热泵干燥装置中干燥介质的物性及其应用分析

在热泵干燥装置中,干燥介质对干燥过程的传热传质速率、物料干燥质量和装置的能源效率均具有重要影响。给出了空气、氮气、二氧化碳、氩气、氢气、氦气六种干燥介质的热物性数据及其计算方程,并分析了其适宜的应用场合,为热泵干燥装置中选择适宜的干燥介质提供了较好的参考。     

内加热式热泵干燥装置的设计

内加热式热泵干燥装置通过导热加热方式提供物料中水分气化所需热能,可获得较高的能源效率和除湿能耗比。在介绍内加热式热泵干燥装置基本结构和工作过程的基础上,给出了其物料衡算、能量衡算和主要部件选型参数的计算公式,为内加热式热泵干燥装置的设计提供了较好的参考。     

水循环式热泵干燥装置的性能分析

水循环式热泵干燥装置是指热泵和干燥部分通过水循环耦合而成的热泵干燥系统，是一种中小型热泵干燥装置的结构型式。对水循环式热泵干燥装置的开机过程、调控特性、能源效率进行了分析，相关结论可为推广应用提供参考。     

热泵干燥装置的调控分析

热泵干燥具有节能、低温干燥及环境友好等特点，控制热泵干燥装置运行在较佳的状态，是保证热泵干燥装置效率和可靠性的基础。以带循环空气旁通的封闭式热泵,干燥装置为例，对热泵干燥装置的调控方法进行了分析，给出了装置的被控参数和一组较佳的控制参数，并建立了各控制参数的计算公式。     

蒸汽与热泵联合干燥木材的匹配分析

对单独的常规蒸汽干燥、热泵(除湿)干燥以及二者联合干燥三种工况进行了能耗分析，结果以联合干燥能耗最低，热泵(除湿)干燥次之，常规蒸汽干燥能耗最高。文中还就相应干燥条件下蒸汽-热泵(除湿)联合干燥的匹配条件作了研究。     

热泵干燥装置的应用和发展分析

在简要介绍热泵干燥装置基本结构和工作原理的基础上，对热泵干燥装置的特点、市场拓展、应用与推广中的主要问题和解决思路、技术发展等进行了较全面的分析，为科学地把握和应用热泵干燥技术提供了较好的参考。     

太阳能辅助型热泵干燥装置的设计与试验

热泵干燥装置作为节能、环保的新型干燥装置具有高效节能、常压低温干燥、结构形式多样、无污染等特点而得到广泛应用.但热泵干燥装置在闭式循环中,前期启动和后期降速阶段存在不足:前期预热过程缓慢、启动时间长、启动阶段效率低;后期降速阶段的干燥速率低、干燥物料品质不高.本论文利用太阳能与热泵结合,提高干燥效率.     

热泵干燥装置

本文综合介绍热泵干燥装置的工作原理、特点及其典型的流程，并对热泵干燥装置进行分类；最后介绍几种热泵干燥装置的应用情况。     

水循环式热泵干燥装置的设计分析

水循环式热泵干燥装置是指热泵和干燥部分通过水循环耦合而成的热泵干燥装置,是一种较适宜于中小型热泵干燥装置的结构型式。以典型的物料干燥工艺为基础,对水循环式热泵干燥装置的冷却器、加热器、冷水循环部分、热水循环部分、热泵部件及工质的设计进行了分析和讨论,为水循环式热泵干燥装置的应用提供了较好的基础。     

氢气作为热泵干燥装置干燥介质的分析

分析了氢气作为热泵干燥装置干燥介质时,干燥介质与物料的对流换热系数、对流传质系数、干燥介质的流动阻力、单位体积干燥介质与水蒸气的饱和混合物中的水蒸气量、单位体积干燥介质在绝热干燥过程中的最大水蒸气吸收量等特性,并与空气作为干燥介质时进行了对比,为氢气型热泵干燥装置的开发提供了较好的参考.     

Drying of biofuels from the forest—A review

The literature during 2000–2016 about drying of biofuels from the forest has been reviewed. Biofuels constitute a low-cost energy resource that is likely to continue to increase and the dryers for such products should be simple, robust, and easy to operate. In 1970s and 1980s, rotary dryers and flash dryers were the most common types, and in 1990s, superheated steam (SHS) dryers became common. Maintenance costs and use of medium pressure steam for the SHS dryers are important topics to consider and one drawback for the rotary dryers is that high-temperature heat sources are used. The development during the last 15 years has moved toward moving bed dryers because of the possibility to use cheap low-temperature energy sources, robust design, and direct capacity control that is achieved by controlling the air temperature in the dryer. A price for the dry biofuel of 15–20 Euro/MWh has been indicated to make a dryer installation profitable based on no cost for the thermal energy and 40 Euro/MWh as the cost for the electrical energy. Shrinkage and the internal transport of moisture and heat in large particles of biofuels will need more considerations in the future. Fractionation of the biofuels, codrying with other products, the total cost for the drying process, environmental issues, and development of drying processes operating at high dew points are the other things to consider.     

Modeling of heat pump tumble dryer energy consumption and drying time

The use of heat pump tumble dryers is nowadays more common because they offer huge energy savings compared to conventional tumble dryers. Earlier studies made on conventional tumble dryers have shown that parameters such as heater power, fan speed, drum speed, weight and initial moisture content of textiles and air leakage have a huge impact on the energy efficiency and drying time. In the present study, a modified commercial heat pump tumble dryer was evaluated for energy consumption and drying time by changing operating parameters including fan speed, drum speed, and mass load. The total energy consumption and drying time were measured and corrected for the initial and final moisture content in the textiles. The experimental results based on 27 drying tests were evaluated to develop linear regression models for energy consumption and drying time, which show a good agreement with the experimental data. The results show that a large mass load, a high drum speed, and a low fan speed give the highest energy efficiency, i.e. the lowest energy consumption per kg of drying load. Larger loads extend the length of the drying cycle while higher fan and drum speeds result in shorter drying time.     

Model‐Based Energy Efficiency Optimization of a Low‐Temperature Adsorption Dryer

Low‐temperature drying is important for heat‐sensitive products, but at these temperatures conventional convective dryers have low energy efficiencies. To overcome this challenge, an energy efficiency optimization procedure is applied to a zeolite adsorption dryer subject to product quality. The procedure finds a trade‐off between the improved drying capacity due to dehumidification and energy expenditure due to regeneration while incorporating product drying properties. By optimizing the regeneration air inlet temperature, drying air, adsorbent, and regeneration air flow rates as well as sensible and latent heat recovery from the regenerator exhausts, the energy efficiency is improved by up to 45 % compared to the state‐of‐the‐art. The high mass transfer effect of high temperatures is utilized in the regenerator to boost dehumidification while isolating the heat‐sensitive dried product from the quality‐degrading effect.     

Calculation Steps for the Design of Different Components of Heat Pump Dryers Under Constant Drying Rate Condition

Heat pump–assisted dryers are an alternative method for drying heat-sensitive food products at low temperature and less relative humidity with lower energy consumption. The mathematical models of a heat pump dryer consist of three submodels; namely, drying models, heat pump models, and performance models. Heat and mass balance of both refrigerant and air circuits in all components of the system are used for development of mathematical models. The models are used for design of different components of heat pump dryers operating under constant drying rate condition. A simple stepwise design procedure for batch-type, closed-loop heat pump dryer is also presented.     

回热式热泵干燥高湿稻谷的试验研究

应用带有嵌入回热器的热泵装置,对华南地区高湿稻谷进行干燥试验,测定其干燥速率、能耗和品质。并与同期作业的燃油低温循环稻谷干燥机进行对照。试验结果表明：回热式热泵干燥机的干燥速率较燃油低温循环干燥机提高20％,干燥周期缩短约12％,而干燥能耗及费用可节省30％以上,干燥品质两者无差异。     

Drying of Guava and Papaya: Impact of Different Drying Methods

Heat pump dryers (HPD) are known as high-energy-efficiency devices with low economic cost. As it is usually a closed system, the drying media can be substituted by inert gases. In this study, the effect of nitrogen and carbon dioxide on guava and papaya were investigated. Both drying kinetics and quality of these dried fruits resulting from the two methods were compared with normal air HPD, vacuum dryer, and freeze dryer. When using CO₂, the effective diffusivity during the drying process was 44% higher in guava and 16.34% higher in papaya. There was less browning, faster rehydration, and more vitamin C retention in the final products. All these reveal the great potential of modified atmosphere heat pump dryer in the food drying industry.     

塔形连续式真空干燥设备节能方向的分析

以塔形连续真空干燥设备为研究对象,从传热、设备结构、配套装置和能源利用的角度分析节能减排的方向与途经。     

国内炼油企业低温热利用现状

综述了近年来国内炼油企业为降低企业能耗、提高经济效益而普遍开展的低温热综合利用现状，着重介绍了常减压装置、催化裂化装置、焦化装置、加氢装置及蒸汽凝结水等主要低温热源的回收利用情况。从现有情况看，国内炼油企业节能降耗成果显著，并取得了良好的经济效益和社会效益。     

A Novel Atmospheric Freeze-Drying System Using a Vibro-Fluidized Bed with Adsorbent

Atmospheric freeze drying (AFD) in a vibro-fluidized bed dryer coupled with an adsorbent and multimode heat input is proposed for dehydration of food products at lower cost than the traditional freeze-drying process under vacuum. The aim of this project is to study the proposed AFD system using a vortex tube to produce low-temperature dry air, an alternative for producing dried food products of high quality. An experimental setup was designed and built to permit simultaneous application of convection, conduction, and radiation heat input to the drying material above its freezing point to ensure sublimation. A parametric evaluation over a broad range of possible parameter values was carried out using cubic-shaped potato and carrot as model heat-sensitive products. The influence of various system parameters on drying kinetics, quality, and functional properties of the dried products (color, rehydration properties, and morphology) were investigated. Comparison between physical quality and drying characteristics of the AFD system with AFD using fixed bed, fluidized bed dryer, and also with traditional vacuum freeze drying were carried out to investigate the viability of this new system. Results indicate that proposed system is an alternative to reduce the process time as well as to maintain the product quality at lower cost.