基于遗传算法的双热源热泵污泥干燥系统

针对污泥热干化技术能耗高、污水余热未高效利用等问题,设计一种基于遗传算法的双热源热泵污泥干燥系统。结合遗传算法优化热泵工作参数,提高热泵对不同季节水温以及系统运行不同阶段的余热回收效率。废气源和污水源的双热源热泵余热回收,充分利用干燥废气和城市污水的余热用于污泥干燥,降低能耗。根据污泥干燥动力学,对干燥室风量进行分配,提高污泥干燥效率。双热源热泵污泥干燥系统应用于市政污水处理厂,针对污水处理过程中产生的污泥进行干燥处理,利用废气和污水余热,降低污泥热干化能耗,是推广污泥处理技术、适应城市发展优化污泥处理的一种选择,具有良好的节能减排效益和社会效益。     

基于自回热理论的稻谷流化床干燥系统设计及研究

为了解决传统稻谷流化床干燥系统能耗过大的问题,应用自回热理论设计了一套新的稻谷流化床干燥系统,对传统系统及新系统进行了能耗分析对比,并对影响其热力性能的关键参量进行了分析。结果表明:由于应用了自回热理论,回收了流化床出口处低温湿空气的潜热,并将其作为加热干燥介质的热源,相比于传统干燥系统,自回热稻谷流化床干燥系统更有显著的节能优势。自回热系统的净能耗比传统系统降低了53.39%。传统干燥系统温度为110℃,自回热干燥系统仅为86.7℃,使稻谷这种热敏性的物料有更好的品质。另外,对自回热干燥系统中压缩机压比和绝热效率进行研究表明:压比越大,自回热干燥系统的净能耗越大;绝热效率越高,自回热系统的节能性更好。     

干燥过程节能

干燥过程是指通过干燥介质利用热能除去含湿物料的湿份。干燥介质通常为空气、烟气,也有的采用过热蒸汽或惰性气体,被除去的湿份大多是水。干燥操作在工农业生产中获得了广泛应用,用于干燥的能量消耗相当可观。例如,英国消耗于干燥过程的能量为其全国工业能耗的7％;苏联更高,在全苏的燃料平衡中,用于干燥的燃料约占总量的10％。目前,干燥过程的能量利用率是比较低的,如干燥药片包衣的热效率只     

污泥带式干化系统的理论研究

带式干燥机由于其干化性能优,可利用多种不同品质的热源,被广泛应用于食品、水果、污泥等湿物料的干燥.本文以处理规模为60t/d湿污泥的带式干化系统为研究对象,基于物料及能量守恒理论,分析了带式干化系统的物料与能量特征,及废气内循环率对系统能耗的影响.分析结果表明,带式干化系统将污泥含水量从80％降至35％时,污泥蒸发出来的水分为 1730.8kg/h,脱水率为69.23％,污泥减量化明显.当废气内循环风比率为75％时,单位污泥水分蒸发消耗的蒸汽量为2094.4kg/h,相较于无废气内循环,单位蒸发水能耗降低了 13.37％,具有明显的节能效果.     

应用于食品干燥的热泵性能实验研究

在热泵干燥系统中,热泵性能对干燥能耗和干燥食品品性有显著影响。热泵干燥系统的干燥温度是干燥过程的关键参数之一。本文对比测试各种升温方式的基础上,主宰了带辅助蒸发器在热泵干燥机组不仅升温速度快,能耗低,除湿效果显著,而且可以满足不同食品干燥要求。     

大型计算机机房空调系统的节能改造

本文对一大型计算机机房集中式空调系统改造为普通分体柜式空调机组的可行性作了理论分析；详述了该机房的改造过程；对该机房改造前后空气温湿度的控制精度、能耗、维修管理费用作了对比。为今后新建大型或特大计算机房采用普通分体柜式空调机作为人工冷热源或现有大机房的类似改造提供了可资代览的依据。     

多模式再生运行的热源塔热泵系统运行能效分析

针对常规建筑空调冷热源形式的不足之处,采用多模式再生系统改善常规热源塔热泵系统,详述其工作原理、工作模式和系统设计方法。在实际节能改造项目中应用该系统并给出控制策略与评价计算方法,对制冷、制热和吸湿的典型工况进行现场实际测试,结果表明:在该系统设计参数下,夏季平均空气温度28.6℃、平均相对湿度84.5%工况综合制冷效率为4.51,冬季平均空气温度7.68℃、平均相对湿度81.2%工况考虑再生能耗在内综合制热效率为3.46。系统运行过程中溶液吸湿量与环境温度和相对湿度有关,环境温度越高,相对湿度越低,吸湿量越小。热源塔吸热由显热和潜热两部分组成,潜热占比受运行过程吸湿量影响,与空气相对湿度直接强相关,相对湿度越低,空气与水接触面水蒸气分压力差越小,水分更难从空气迁移到溶液中。测试时间内平均相对湿度81.2%的工况下由溶液吸湿导致的潜热占总系统热量比例约为18.6%。再生机组再生效率高低受外界环境与工况变化的影响较小,5天内平均值为4.45 kg/kWh。     

秸秆直燃发电的生命周期评价

应用生命周期评价(LCA)方法,以秸秆直燃发电项目为研究对象,对秸秆的种植、运输、粉碎干燥和燃烧发电等4个过程进行了清单分析,并分别计算出4个过程的能耗及其对环境的影响.结果表明,每燃烧100kg秸秆发电,对环境的总影响负荷水稻秸为247.36毫人当量,小麦秸为268.74毫人当量,玉米秸为267.33毫人当量.秸秆直燃发电对环境影响主要为烟尘和灰尘,对局部地区的影响占据首位.以水稻秸秆为例,100kg水稻秸秆在直燃发电过程中整个系统共从环境吸收CO2167.60kg,向环境释放CO2164.24kg,由此看到,秸秆直燃发电项目在减少温室气体排放上能起积极作用.     

拼装式太阳能空气集热器的发展与应用

在工农业的许多生产部门和国防工程中,干燥或除湿是必不可少的,其能耗很大。1975年以来,我国逐渐开展了太阳能干燥和除湿的研究,取得了较好的社会效益和经济效益。目前全国已建成约150个太阳     

基于中温热泵的消防水带干燥装置性能研究北大核心CSCD

为研究消防水带的干燥特性曲线,实现低能耗、快速干燥的目的,文章研发了以R134A为制冷剂的中温热泵消防水带干燥装置。通过实验方法分析消防水带干燥特性,并对该中温热泵消防水带干燥装置的性能开展研究,对比不同送风温度、风速下,系统性能系数(COP)、制热量、干燥时间、干燥过程耗电量、单位能耗除湿量(SMER)、单位时间除湿量(MER)的变化规律。结果表明,在一定范围内,随着送风温度的增加,COP降低、SMER和MER均升高。风速不变,送风温度为70℃时,干燥性能最优,SMER为0.427 kg/(kW·h),MER为1.584 kg/h,比送风温度为40℃时提高了10.9%和62.1%。送风温度不变,风速为4 m/s时,干燥效果最好,SMER为0.543 kg/(kW·h),MER为1.137 kg/h,比风速为2 m/s时提高了20.4%和50.2%。送风温度为50℃时,比消防水带吹干机节能约52%。     

太阳能-空气源热泵联合干燥系统设计及干燥枸杞的实验研究

为缩短枸杞干燥时间,提高干制枸杞的质量,减少能源消耗,本文提出了一种新型太阳能–空气源热泵联合干燥系统。该系统主要由太阳能集热器和空气源热泵机组等设备组成,可以实现太阳能单独干燥、热泵单独干燥和太阳能–空气源热泵联合干燥三种工作模式。本文根据枸杞的干燥特性,分段设定最佳的干燥温度,进行了热泵单独运行和太阳能–热泵联合运行两种工作模式下干燥枸杞的对比实验。结果表明,干燥50 kg枸杞,太阳能–热泵联合运行比热泵单独运行节省了2.9 kW?h电能,若同时除去系统本身的耗能,节省的电能占热泵单独运行耗电量的29.5%。同时,与太阳能单独干燥相比,太阳能–热泵联合干燥具有较高的除湿能耗比,两者最大差值为0.71 kg/(kW?h)。本文提出的太阳能–热泵联合干燥系统具有提高干燥产品的品质、缩短干燥时间和节约干燥成本等优点,适宜推广。     

Review of solid/liquid desiccant in the drying applications and its regeneration methods

Desiccant material has been used in drying applications because of its low energy consumption, among other advantages. Desiccant material can produce hot and dry air that is beneficial for the drying process. The advantages of using desiccant material in a drying system include continuous drying even during off-sunshine hours, increased drying rate due to hot and dry air, more uniform drying, and increased product quality especially for heat-sensitive products. Some problems in desiccant system such as pressure drop in solid desiccant, carry over of liquid desiccant by air stream and low moisture adsorption capacity may be improved by optimization of the design of desiccant system. Numerous researchers have studied the low cost and low regeneration temperature of desiccant material, and the optimization of desiccant application to produce more competitive energy. The use of heat to regenerate desiccant material in a drying system has limitations in energy saving. However the use of low energy or free available energy such as solar energy and waste heat from industrial processes for regeneration of desiccant material will make the system more cost-effective. This paper presents several works on the regenerative method of the desiccant system and its application in the drying system for both solid and liquid desiccant materials.     

Exergy analysis of industrial pasta drying process

In this study we present an energy and exergy modelling of industrial final macaroni (pasta) drying process for its system analysis, performance evaluation and optimization. Using actual system data, a performance assessment of the industrial macaroni drying process through energy and exergy efficiencies and system exergy destructions is conducted. The heat losses to the surroundings and exergy destructions in the overall system are quantified and illustrated using energy and exergy flow diagrams. The total energy rate input to system is 316.25 kW. The evaporation rate is 72 kg h^?1 (0.02 kg s^?1) and energy consumption rate is found as 4.38 kW for 1 kg water evaporation from product. Humidity product rate is 792 kg h^?1 (0.22 kg s^?1) and energy consumption rate is found about 0.4 kW for 1 kg short cut pasta product. The energy efficiencies of the pasta drying process and the overall system are found to be as 7.55–77.09% and 68.63%. The exergy efficiency of pasta drying process is obtained to be as 72.98–82.15%. For the actual system that is presented the system exergy efficiency vary between 41.90 and 70.94%. Copyright © 2006 John Wiley & Sons, Ltd.     

基于蒸汽再压缩技术的低温干燥系统设计与节能分析

为了解决干燥行业热效率低下的问题,本文将机械蒸汽再压缩技术引入热敏性物料的低温干燥领域,设计了一种新型低能耗低温干燥系统,并采用夹点分析技术对新型低温干燥系统的热力性能进行了优化。计算结果表明,所设计的新型低温干燥系统能耗为19.57 kW,与相同条件下的常规低温干燥系统相比,新型干燥系统的能耗仅为常规低温回热干燥系统的7.7%。同时,系统能耗随着蒸发温度与压缩机压比的降低而不断下降。所做工作为低温干燥系统的性能分析及优化提供了参考。     

Response surface optimization of a novel pilot dryer for processing mixed forest industry biosludge

As a promising sludge handling alternative capable of utilizing the secondary energies in industrial environments, we investigated the use of a novel pilot‐scale cyclone dryer for processing industrial mixed sludge from the forest industry. Attainable sludge dry solids contents (%) and respective specific energy consumption of drying (kWh kg^?1 H₂O) were successfully modelled by response surface methodology based on a constructed design of experiments. Predicted sludge dry solids and the specific energy consumption of drying varied between <30–65% and <0.4–1.8 kWh kg^?1 H₂O depending on controlled inlet air temperature, sludge feeding rate and humid air recirculation levels. The response models were further optimized for efficient combustion of processed sludge with inlet air temperatures corresponding to potentially available secondary heat. According to the results, energy efficient drying of mixed sludge with a specific energy consumption <0.7 kWh kg^?1 H₂O can be performed with inlet air temperatures ≥60 °C corresponding with pilot‐scale feeding capacities between 300–350 and 550 kg h^?1 depending on inlet air temperature. These findings suggest that the introduction of novel drying systems capable of utilizing the available secondary energies of industrial environments could significantly improve the energy efficiency of sludge drying and potentially allow considerable cost savings for industrial operators. Copyright © 2015 John Wiley & Sons, Ltd.     

Evaluation of energy efficiency in biofuel drying by means of energy and exergy analyses

The calculation of heat consumption is based on the First Law and it gives quantitative information about the energy used in drying. However, it does not pay any attention to the quality of the energy used in drying. To take into account the quality of the energy, attention must be paid to the Second Law, too. Especially in those cases where the energy used in drying may be converted to mechanical work, it is important to consider the Second Law is. In this paper, the energy efficiency of biofuel drying in a pulp and paper mill is evaluated on the basis of energy and exergy analysis. The evaluation is based on the determination of the heat consumption and the irreversibility rate for energy and exergy analysis, respectively. The evaluation methods are applied to two different drying systems, single-stage-drying with partial recycle of spent air, and multi-stage-drying. Both drying systems are also provided with a heat recovery unit in which the inlet air is pre-heated using the outlet air of the dryer. There are two alternative heat sources available for the drying energy, steam at a pressure of 3 bar and water at a temperature of 80 °C. The results show that the heat consumption is only dependent to a small extent on the heat source type or the drying system. On the other hand, the irreversibility rate depends to a considerable on the heat source and the drying system.     

Analysis of a new drying chamber for heat pump mint leaves dryer

Drying is an energy intensive and time consuming process, so reducing amount of demanded energy and drying time are important issues for drying technology. The main aim of this paper is to analyze the drying characteristics of mint leaves in a new cylindrical form of drying chamber at low drying air temperature and by emphasizing on energy analysis. The dryer consists of air source heat pump system, air to air heat recovery unit and proportional temperature controller. Experiments were performed at 2, 2.5 and 3 m/s air velocities and at 35 °C cabin inlet air temperature. Mint leaves were dried from 9 g water/g dry matter to 0.1 g water/g dry matter. Designed drying chamber, with three stainless steel cylinders in circular nested form, has a positive effect for drying technology. This system has some advantages such as: drying of product by accessing a uniform air flow and preventing spread of light weight samples like mint leaves over drying system. Calculations based on experimental data show that in the best case, by consuming 3.164 kWh energy in a heat pump with 3.94 coefficients of performance, 4.56 kWh energy had been gained by heat recovery unit. Average 48% of energy was saved by means of heat recovery unit. Effective moisture diffusivity values varied from 3.50E?11 to 5.88E?11 for mint leaves.     

Drying and heat transfer behavior of banana undergoing combined low-pressure superheated steam and far-infrared radiation drying

The present study aimed at investigating the use of a drying system combining the concept of already proven low-pressure superheated steam drying and far-infrared radiation (LPSSD–FIR) for banana. The effects of various operating parameters, i.e., drying medium temperature and pressure, on the drying kinetics and heat transfer behavior of banana as well as the energy consumption of the process were investigated and discussed. Comparison was also made with similar sets of data obtained from the system with combined far-infrared radiation and vacuum drying (VACUUM–FIR) and the system using only low-pressure superheated steam drying (LPSSD). The results showed that LPSSD–FIR and VACUUM–FIR took shorter drying time compared to LPSSD at all drying conditions. In terms of the specific energy consumption, it was observed that the specific energy consumption of the vacuum pump was much higher than that of the far-infrared radiator or electric heater. It was also found that the specific energy consumption of LPSSD–FIR and VACUUM–FIR were lower than that of LPSSD at all drying conditions. Based on the drying rates and the specific energy consumption of all tested processes, LPSSD–FIR at 90 °C and 7 kPa was suggested.     

A solar assisted heat pump drying system for grain in-store drying

For grain in-store drying, a solar assisted drying process has been developed, which consists of a set including a solar-assisted heat pump, a ventilation system, a grain stirrer, etc. In this way, low power consumption, short cycle time and water content uniformity can be achieved in comparison with the conventional method. A solar-assisted heat pump drying system has been designed and manufactured for a practical granary, and the energy consumption performance of the unit is analyzed. The analysis result shows that the solar fraction of the unit is higher than 20%, the coefficient of performance about system (COPS) is 5.19, and the specific moisture extraction rate (SMER) can reach 3.05 kg/kWh.     

A solar assisted heat pump drying system for grain in-store drying

For grain in-store drying, a solar assisted drying process has been developed, which consists of a set including a solar-assisted heat pump, a ventilation system, a grain stirrer, etc. In this way, low power consumption, short cycle time and water content uniformity can be achieved in comparison with the conventional method. A solar-assisted heat pump drying system has been designed and manufactured for a practical granary, and the energy consumption performance of the unit is analyzed. The analysis result shows that the solar fraction of the unit is higher than 20%, the coefficient of performance about system (COP_S) is 5.19, and the specific moisture extraction rate (SMER) can reach 3.05 kg/kWh.