Achieving Cooler Soil as an Effective Heat Sink for Earth-to-Air Heat Exchanger (EAHE) Cooling Technology in Malaysia Tropical Climate

This research is intended to explore the capacity of Malaysia soil in becoming a more effective heat sink for the application of Earth-to-Air Heat Exchanger (EAHE) Cooling Technology in Malaysia. EAHE Cooling Technology consists of buried pipes underground where the ambient air is channeled through from the pipe inlet and produces cooler air at its outlet. Within the buried pipes, heat exchange process occurs between the air and the soil that surrounding the pipe. This building cooling technology has been applied in many countries, mostly in temperate or hot and arid climate where the diurnal temperature is large. However, minimal resources were found on the study of EAHE application to buildings in Malaysia, hence there is room to develop. A parametric study on EAHE cooling application in Malaysia was done through field experiment and concluded that among many parameters affecting the technology performance, the soil temperature which surrounded the pipe was the most influential factor. The study recommended to further reduce the soil temperature to achieve a cooler outlet temperature. In response to that, this research conducted a parametric study of soil temperature under three different soil surface conditions: bare, shaded with timber pallettes and insulated with used tyres at 1.0 m and 1.5 m underground. The data was logged for a month and the result has shown significant reduction in the soil temperature underground below the shaded and insulated soil surface as compared to below bare soil surface condition. The insulated soil surface produced the best result where the soil temperature was reduced up to 26.9°C. The main contribution of this paper is to highlight that the soil surface treatment can be used to reduce solar heat gain within the soil underground and thus improving the performance of EAHE Cooling Technology particularly for the application in Malaysia tropical climate.

A Survey on a Heat Exchangers Network to Decrease Energy Consumption by Using Pinch Technology

There are several ways to increase the efficiency of energy consumption and to decrease energy consumption. In this paper. the application of pinch technology in analysis of the heat exchangers network （HEN） in order to reduce the energy consumption in a thermal system is studied. Therefore, in this grass root design, the optimum value of △Tmin, is obtained about 10℃and area efficiency （a） is 0.95. The author also depicted the grid diagram and driving force plot for additional analysis. In order to increase the amount of energy saving, heat transfer from above to below the pinch point in the diagnosis stage is verified for all options including re-sequencing, re-piping, add heat exchanger and splitting of the flows. Results show that this network has a low potential of retrofit to decrease the energy consumption, which pinch principles are planned to optimize energy consumption of the unit. Regarding the results of pinch analysis, it is suggested that in order to reduce the energy consumption, no alternative changes in the heat exchangers network of the unit is required. The acquired results show that the constancy of network is completely confirmed by the high area efficiency infirmity of the heat exchanger to pass the pinch point and from of deriving force plot.

Improved Efficiency of Heat Exchange Using KELEA Activated Water

An environmental force termed KELEA (kinetic energy limiting electrostatic attraction) is postulated to reduce the strength of intermolecular (hydrogen) bonding of water molecules, resulting in increased kinetic activity of the water. While regular water does not directly absorb KELEA from the environment, various dipolar compounds with separated electrical charges can seemingly act as a primary antenna for KELEA, with secondary transfer of energy into nearby water. Moreover, once sufficiently activated, the separated electrical charges in activated water can apparently function as a receiver for KELEA, leading to further activation of the water and also to the activation of added water. Prior publications have addressed the agricultural and potential clinical benefits of using KELEA activated water. This article is intended as the first in a series of papers describing useful industrial applications of KELEA activated water. The focus of the present paper is on the improved efficiency of industrial water heating and cooling systems by using KELEA activated water provided by pelleted, ground and heated volcanic rock as supplied by Kiko Technology.

Flexibility analysis and design of heat exchanger network for syngas-to-methanol process

The heat exchanger network(HEN)in a syngas-to-methanol process was designed and optimized based on pinch technology under stable operating conditions to balance the energy consumption and economic gain.In actual industrial processes,fluctuations in production inevitably affect the stable operation of HENs.A flexibility analysis of the HEN was carried out to minimize such disturbances using the downstream paths method.The results show that two-third of the downstream paths cannot meet flexibility requirements,indicating that the HEN does not have enough flexibility to accommodate the disturbances in actual production.A flexible HEN was then designed with the method of dividing and subsequent merging of streams,which led to 13.89%and 20.82%reductions in energy consumption and total cost,respectively.Owing to the sufficient area margin and additional alternative heat exchangers,the flexible HEN was able to resist interference and maintain production stability and safety,with the total cost increasing by just 4.08%.

Integration of energy recovery network including recycling residual pressure energy with pinch technology

Work exchange is a promising innovative technology in recovering residual pressure energy. However, at the systematic level, the comprehensive utilization of different energy resources in an energy system has become an issue of concern. In this work, a systematic approach is proposed, one that successively integrates heat, work and adjusts operation parameters. A detailed procedure for building a heat-work coupling transfer network is provided. The synthesis mainly consists of constructing a work exchange sub-network with pinch analysis based on positive displacement type work exchangers. Simultaneously, another kind of sub-network based on turbine-type work exchangers is built as a schematic comparison. The influence of applying a positive displacement work exchanger on the system is investigated. Finally, as a case study, a renovation design of a typical rectisol process in the coal-water slurry gasification section of an ammonia plant is presented. The results show that the added work exchanger has little impact on the existing heat exchange sub-network. Moreover,extra pressure energy is recovered by coupling the transfer network. It is concluded that the heat-work systematic design is a promising and powerful method to use energy more efficiently.

Simulation and heat exchanger network designs for a novel single-column cryogenic air separation process

To realize the industrialization of the novel single-column air separation process proposed in previous work,steady-state simulation for four different configurations of the single-column process with ternary(nitrogen,oxygen and argon)is developed.Then,exergy analysis of the single-column processes is also carried out and compared with the conventional double-column air separation process at the same capacity.Furthermore,based on the steady-state simulation of single-column processes,the different heat exchanger networks(HENs)for the main heat exchanger and subcooler in each process are designed.To obtain better performance for this novel process,optimization of process configuration and operation is investigated.The optimal condition and configuration for this process is consisted as:feedstock is divided into two streams and the reflux nitrogen is compressed at the approximate temperature of 301 K.In addition,HEN is optimized to minimize the utilities.HENs without utilities are obtained for the four different configurations of single-column process.Furthermore,capital costs of the HEN for different cases are estimated and compared.

Review on Anti-Frost Technology Based on Microchannel Heat Exchanger

Frosting is an inevitable adverse phenomenon in many fields such as industrial refrigeration,cryo-genics,and heat pump air conditioning,which may influence the efficiency of the equipment and increase the energy consumption of the system.The complicated louvered-fin structure and fuid-channels arrangements of the microchannel heat exchanger(HEX)will affect the heat transfer performance and frosting characteristics.First,this article analyzes different factors such as refrigerant distribution,refrigerant fow pattern,and HEX surface temperature distribution.Further,combined with the features of the microchannel HEX,the existing anti-frosting technologies and various methods of surface treatment for anti-frosting are summarized.The review focuses on the preparation of superhydrophobic surfaces and their superior properties.Furthermore,the internal mechanism is analyzed in conjunction with the relevant research of our group.Superhydrophobic character has excellent anti-frosting performance and heat transfer performance,which is of great significance for improving energy-saving and system performance.Finally,the future development of superhydrophobic surface technology is analyzed and prospected.

Distribution optimization of circulating water in air-cooled heat exchangers for a typical indirect dry cooling system on the basis of entransy dissipation

The flow and heat transfer of air-cooled heat exchangers play important roles in the performance of indirect dry cooling systems in power plants,so it is of benefit to the design and operation of a typical indirect dry cooling system to optimize the thermo-flow characteristics of air-cooled heat exchangers.The entransy dissipation method is applied to the performance optimization of air-cooled heat exchangers in this paper.Two irreversible heat transfer processes in air-cooled heat exchangers,the heat transfer between circulating water and cooling air and the mixing of circulating water,are taken into account and analyzed by means of the entransy dissipation method.The total entransy dissipation rate,which connects the geometrical parameters of air-cooled heat exchanger sectors and the heat capacity rates of the fluids to the heat flow rate in every sector,is obtained.Based on the mathematical relation and the conditional extremum method,an optimization equation group is derived,by which the air-cooled heat exchanger with known air-side parameters is optimized,showing that the entransy dissipation based optimization approach can contribute to the distribution optimization of circulating water in air-cooled heat exchangers of a typical indirect dry cooling system.

离子液脱硫技术中热平衡的研究与实践

介绍了离子液脱硫系统的工艺流程,分析了系统运行中的热交换过程,主要换热设备采用板式换热器,针对换热过程中出现的热平衡被破坏的情况及影响进行探讨,提出了保持离子液脱硫系统稳定运行的措施。

管壳式换热器管束的搪瓷涂层防腐技术研究

随着生产工艺水平的提高,换热器工作环境的温度、压力和流体高速流动所产生的应力都随之提高,同时介质的腐蚀性也随之提高,因此防腐性能较强的换热器成为刚性需求。文中对换热器管束进行防腐技术研究,选用搪瓷涂层对管束进行腐蚀防护;研究了管束表面搪瓷涂层的加工工艺,验证了搪瓷涂层的防腐性能及热震性能,结果良好;提出搪瓷管束与管板新连接加工工艺,取代了原有的先胀后焊的加工工艺,并加以验证,效果良好。

潜热储热技术研究现状与发展趋势

潜热储热技术可实现能源持续供应,但其潜热材料和换热器装置因储热性能差、成本高等问题制约了储热产业发展,亟需解决相关技术难题提高热能利用效率。介绍了潜热储热的主要体系及分类;综述了潜热储热技术原理、材料选择以及换热器翅片设计;阐述了潜热储热技术在太阳能、工业余热回收、谷电利用领域的工作原理。现有潜热储热相关研究主要通过优化换热器结构、改良潜热材料、设计新型储热系统提高储热效率和能源利用率。未来,可开发潜热材料回收再利用系统、强化储热与其他能源耦合、优化储热装置和热管理系统等方面提高潜热储热技术。

深层埋管换热技术研究热点与发展趋势分析

为动态分析深层埋管换热领域研究热点与前沿发展趋势,运用可视化知识图谱分析软件,将近23年CNKI和WOS数据库中与深层埋管研究相关的学术性文献作为数据源,分别从发文量、国际核心机构和关键词等进行文献计量与内容分析,解析该领域的研究热点和前沿分析。研究结果表明:2000年以来深层埋管研究领域的文献发文量逐步上升,核心作者及机构之间的合作仅为单线或团队内部之间,跨机构之间较少;研究热点和趋势具有阶段性特征,不同阶段的研究重点不同。随着地热能+、“双碳”目标和“十四五”可再生能源发展规划等一系列战略决策及清洁能源高效利用理念的提出,深层埋管换热领域的研究热点更聚焦于交叉学科的渗透和技术方法的创新,国内深层埋管换热技术未来的发展趋势表现为开采技术突破、换热器类型及材质方面的创新与探索、研究方法优化和外扩中深层地热、综合效益评价等新的研究方向,国外则侧重于换热性能、热泵系统、深层埋管换热器和数值模拟等方向。相关数据可为深层埋管换热技术相关学者的研究工作提供借鉴。

基于夹点分析技术的常减压塔换热网络优化

本文采用夹点技术对某炼油厂常减压装置现有生产工况下的换热网络进行分析优化并提出改进方案。应用Aspen plus建立了常减压塔模型及相应的换热网络,计算各侧线流股流量和物性数据。利用Aspen Energy Analyzer计算得到该换热网络的夹点温度。通过夹点温度来分析诊断换热网络中跨越夹点物流,确定换热网络中瓶颈的位置。通过调整不合理配置的冷热流股换热器来优化换热网络,使脱盐原油进入常压塔的换热终温从288.0℃提高到310.4℃,优化后的冷、热公用工程用量各减少2808.0kW,显著降低了装置的操作费用。

某挠性管板列管式换热器制造工艺技术简介

某项目中的换热器为新型挠性管板列管式换热器,该换热器采用挠性管板结构,换热管为大直径厚壁管。本文介绍了该换热器的结构特点、制造难点,并提出了相应的工艺措施,完成了产品制造,为同类产品积累了制造经验。

地热能利用技术研究进展综述

地热能作为5大非碳基清洁能源之一,具有储量大和分布广泛等特点。概述了地热能利用技术分类及发展现状,并进一步介绍了浅层地源热泵技术、水热型供热系统、中深层地埋管供热技术以及增强型地热系统的基本概念及发展应用现状。对国内外现今地热能利用技术研究进展及最新研究方向进行综述,从行业重难点问题攻关、多场景地热能利用适应性方案开发、地热储能技术探索等方向对中国未来地热能利用技术的研究与发展做出展望,以期为中国地热领域从业人员提供指导建议与意见参考。

Application of self-adaptive temperature recognition in cold-start of an air-cooled proton exchange membrane fuel cell stack

The Self-adaptive control of the temperature can achieve the start of fuel cell at different operating temperatures, which is very important for the successful cold-start of the air-cooled PEMFC. The temperature distribution characteristics during the cold-start process were analyzed based on adaptive temperature recognition control in this paper. Preheating model and cold-start model were established and the optimal balance between the hot air flow rate and the temperature required to promote a uniform temperature distribution in the stack was explored in the preheating stage. Finally, the non-equilibrium mass transfer, as well as the temperature rise in the catalyst layer and gas diffusion layer with different current densities, were analyzed in the start-up stage. The results indicate that the air-cooled PEMFC stack can be successfully started up at -40 ◦C within 10 min by means of external gas heating. The current density and air velocity have significant impacts on the temperature of aircooled PEMFC stack. Dynamic analysis of air-cooled PEMFCs and real-time monitoring are suitable for machine learning and self-adaptive control to set the operation parameters to achieve successful cold start. Optimize the matching of load current and cathode inlet speed to achieve thermal management in low temperature environment.

工商制冷空调用换热器技术现状与发展趋势

为了进一步促进我国工商制冷空调用换热器性能和可靠性的发展,以及制冷剂替代的研究,基于对我国工商制冷空调用换热器的调研,深入分析了换热器(管壳式换热器、板式换热器、翅片管式换热器、套管式换热器、微通道换热器等)的技术现状,并对其技术发展趋势进行展望;指出了目前我国工商制冷空调用换热器在强化换热技术、加工制造工艺等方面取得的进步,但随着应用市场的需求多样化,对换热器提出了更高的技术要求,今后换热器研发应从节材、新型制冷剂研发、加工制造智能化等方面着手,以提高换热器传热效率并节约材料成本,适应制冷剂替代的行业发展趋势。

合金材料在储能技术中的应用与发展

铝硅合金相变材料的密度和热导率高,稳定性强,在储能储热系统中有着极大的研究价值和应用潜力。本文针对铝硅合金材料在储能领域的应用发展进行综述,文章首先回顾了铝硅相变材料国内外研究实例,总结核心物理参数,以此为基础提出相变储热材料与换热技术的研发方向,包括容器材料稳定性、铝硅相变物理性以及相变蓄热器的结构优化,最后总结了铝硅合金的未来应用发展方向。

大型石墨列管换热器换热管装配技术研究

为了解决大型石墨列管换热器换热管装配过程中遇到的主要技术问题,包括换热管的装配错位、无法转动和管板粘结等问题,以提高换热器的装配精度和操作效率,文章通过采用高精度的自动化装配线、改进管材加工工艺以及优化粘结剂和表面处理技术,对装配过程中的关键技术环节进行了系统的分析和优化。实验结果表明,自动化装配技术显著减少了装配错位,精确的设计公差和温度监控系统有效解决了换热管的转动问题。改性环氧树脂粘结剂和等离子体表面处理显著提高了管板的粘结强度。

硫酸装置转化工序换热器复合清洗技术的研究与应用

某公司铅锌冶炼烟气制酸装置转化工序管壳式换热器管程和壳程被酸性胶泥状污垢堵塞,管程和壳程压力降不断升高,换热器总传热系数降低,导致换热器换热效果差,电耗逐渐升高。介绍了该公司采用复合清洗技术清洗堵塞的换热器管程和壳程的步骤、技术要求和注意事项,清洗后,降低了换热器管程和壳程压降,提高了换热效率,促进了转化系统自然平衡,降低了电耗。