有机热载体炉烟气余热回收技术浅析

长期以来,有机热载体炉排烟温度偏高,造成大量的能源浪费,严重影响了锅炉运行的经济性。为减少热能损失,对烟气余热回收技术的可行性方案、工程应用实例进行了阐述;并指出通过锅炉烟气余热利用技术回收排烟中的显热和潜热,可以大大提高有机热载体炉的热效率,实现节能降耗。     

车用液化天然气加热器性能的试验研究

对天然气加热器进行了台架试验。因气态燃料极易与空气混合燃烧,故不易在热交换器内壁产生积炭和烟灰,其热效率比燃油加热器高10%以上。为了消除高温燃气因流动短路而造成的热损失,尝试了在热交换器肋片出口端面增加燃气均流环并进行了试验。另外,为了削弱热辐射及传导所造成的热能流短路损失,还做了在燃烧室外加装遮热筒试验,其试验效果显著。     

燃煤粉有机热载体炉的开发设计

燃煤粉有机热载体炉与传统有机热载体炉比较,具有燃料燃尽率高、热效率高、节能降耗等优点,燃煤粉有机热载体炉的研发成功丰富了有机热载体锅炉的型谱.     

A run-around heat exchanger system to improve the energy efficiency of a home appliance using hot water

A significant portion of the energy consumed by many home appliances using hot water is used to heat cold supply water. Such home appliances generally are supplied water at a temperature lower than the ambient temperature, and the supply water is normally heated to its maximum operating temperature, often using natural gas or an electrical heater. In some cases, it is possible to pre-heat the supply water and save energy that would normally be consumed by the natural gas or electrical heater. In order to save the energy consumed by an appliance using water heater, a run-around heat exchanger system is used to transfer heat from the ambient to the water before an electrical heater is energized. A simple model to predict the performance of this system is developed and validated, and the model is used to explore design and operating issues relevant to the run-around heat exchanger system. Despite the additional power consumption by the fan and pump of the run-around heat exchanger system, the experimental data and analysis show that for some systems the overall energy efficiency of the appliance can be improved, saving about 6% of the energy used by the baseline machine.     

高效燃油/气管架式有机热载体锅炉研制

分析国内燃油/气有机热载体锅炉的主流结构及特点,进而论述了高效燃油/气管架式有机热载体锅炉的研制,并介绍其特点。     

新建炼厂设计阶段提高加热炉热效率的措施

在炼油加工过程中,加热炉是能耗大户.对新建炼厂,在设计阶段提高加热炉热效率,对节能减排有重要意义.在设计过程中,采取燃料气脱硫等措施以降低排烟温度、降低空气过刹系数和漏风量等措施以降低过剩空气量、优化设计加热炉衬里以降低散热损失、优化余热回收系统方案和控制方案以提高烟气余热利用率和操作稳定性、利用装置废热预热助燃空气,...     

无机高效传热技术在原油处理设备中的应用

无机传热元件具有启动迅速、导热系数高及均温性好等优良的传热特性。本文首次将无机传热元件应用于油气田高效加热炉,使设计热效率达到92％,钢耗量由平均13t／MW下降到6-8t／MW,设备造价降低15％,并首次将无机高效传热元件应用于原油处理设备,较好地解决了传统设备由于采用火筒直接加热油井产物所导致的结焦、爆管问题,提高了设备的使用寿命和安全可靠性,并使热负荷减少50％以上,燃气量减少50％以上。利用该技术开发出的两种无机传热高效原油处理设备,对油田地面工程建设及生产运行中的节能降耗具有参考意义。     

A review of the performance of double pass solar air heater

Improvement of the thermal performance of a solar air heater can be obtained by enhancing the rate of heat transfer. The thermal efficiency of double pass solar air heater is higher in comparison to single pass with the concept involved of doubling the heat transfer area without increase in the system cost. Numbers of studies have been carried out on the performance analysis of double pass solar air heater provided with heat transfer augmentation techniques viz. using extended surfaces, packed bed, corrugated absorber were reported in the literature and found more increase in the thermal efficiency in comparison to conventional double duct solar air heater. These studies includes the design of double pass solar air heater, heat transfer enhancement, flow phenomenon and pressure drop in duct. This paper presents an extensive study of the research carried out on double pass solar air heater. Based on the literature review, it is concluded that most of the studies carried out on double pass solar air heater integrated with porous media and extended surfaces. Few studies were carried out with corrugated absorber. Further no study has been reported so far on double pass solar air heater with absorber plate artificially roughened from both the sides. Mathematical models based on energy analysis of some configurations of solar air heater have been discussed.     

Experiments of a solar flat plate hybrid system with heating and cooling

Based upon the prior research of the solar hybrid water heater and refrigerator, a new flat plate solar hybrid system with heating and cooling was proposed and experimental prototype device was constructed. With this new hybrid system, the heat and mass transfer can be improved effectively both in desorption process and adsorption process. The conventional flat plate solar water heater collector absorber is immersed inside adsorbent bed in the new hybrid system. The experimental results show that not only the cooling effect can be obtained, but also both the sensible heat of the adsorbent bed and the adsorption heat can be recovered effectively to produce hot water for domestic use. The COP of this new flat plate hybrid system can reach 0.11 and the heat efficiency is about 0.45, this achievement has demonstrated an efficient way of the application of solar energy.     

Natural convection heat transfer from upward-facing plates in saline water

Saltwater or brackish water is used as a coolant in most industries. Therefore, understanding the heat transfer processes and hydrodynamics during the natural convection in saline water is crucial for enhancing the efficiency of a heat exchanger. This study elaborates on the natural convection heat transfer in saline water under atmospheric conditions. A DC power supply is used to regulate the power given to the heater in a liquid pool for thermal analysis. The pool liquid comprises solutions with varying salinity from 0%, 0.2%, 0.5%, and 2%. The effect of varying salinity on the heat transfer coefficient and the thermal aspects encountered during the desalination process is analyzed. The temperature distribution across the surface of the heater is monitored using an infrared camera. It is studied for the solution of different salinities. The heat transfer coefficient and Nusselt number are investigated during natural convection for normal water and salt solution of different concentrations. It is inferred from the study that in the regime of natural convection, there is no significant difference in the Nusselt number for normal water and saltwater for the lower value of temperature difference between the plate and pool. The heat transfer coefficient in 0.2% saline water is higher as compared to the other solutions.     

热处理炉改造与能源梯级利用研究

我国金属热处理行业设备相对落后,存在能源不能高效利用的问题,因此通过改造设备、应用新技术来达到节能目的有着广阔的发展空间。在此背景下提出了一套天然气热处理炉系统改造方案,并通过计算、比较改造前后系统热耗、气耗、热效率,表明新方案在节能方面的优越性,并定性地分析在火用效率方面该方案具有更明显的优势。     

Development and test of combustion chamber for Stirling engine heated by natural gas

The combustion chamber is an important component for the Stifling engine heated by natural gas. In the paper, we develop a combustion chamber for the Stifling engine which aims to generate 3-5 kWe electric power. The combustion chamber includes three main components： combustion module, heat exchange cavity and thermal head. Its feature is that the structure can divide ＂combustion＂ process and ＂heat transfer＂ process into two appar- ent individual steps and make them happen one by one. Since natural gas can mix with air fully before burning, the combustion process can be easily completed without the second wind. The flame can avoid contacting the thermal head of Stifling engine, and the temperature fields can be easily controlled. The designed combustion chamber is manufactured and its performance is tested by an experiment which includes two steps. The experi- mental result of the first step proves that the mixture of air and natural gas can be easily ignited and the flame burns stably. In the second step of experiment, the combustion heat flux can reach 20 kW, and the energy utiliza- tion efficiency of thermal head has exceeded 0.5. These test results show that the thermal performance of com- bustion chamber has reached the design goal, The designed combustion chamber can be applied to a real Stifling engine heated by natural gas which is to generate 3-5 kWe electric power.     

Long-term thermal performance of a two-phase thermosyphon solar water heater

This article investigates experimentally the long-term thermal performance of a two-phase thermosyphon solar water heater and compares the results with the conventional systems. Experimental investigations are conducted to obtain the system thermal efficiencies from the hourly, daily and long-term performance tests. Different heat transfer mechanisms, including natural convection, geyser boiling, nucleate boiling and film-wise condensation, are observed in the two-phase thermosyphon solar water heater while solar radiation varies. The thermal performance of the proposed system is compared with that of four conventional solar water heaters. Results show that the proposed system achieves system characteristic efficiency 18% higher than that of the conventional systems by reducing heat loss for the two-phase thermosyphon solar water heater.     

Distribution of the heat transfer coefficient in convection reflow oven

Nowadays reflow ovens apply forced convection heating with nozzle-matrix blower system which generates numerous heater gas streams. In these types of ovens the heat transfer coefficients of the gas streams determine mainly the efficiency of heating. In this paper a measurement method is discussed which can determine the heat transfer coefficient distribution under the nozzle-matrix of a convection reflow oven. During the experiments, temperature changes have been measured and the heat transfer coefficient has been calculated using the heat equation of the investigated reflow oven. In the first step, the heat transfer coefficient of the heater gas streams has been studied under the nozzle-matrix in function of height. In the second step, the heating efficiency of the nozzle-lines has been compared and the distribution of the heat transfer coefficient has been calculated. The results are confirmed by a theoretical model. It is also presented that how the contamination of the nozzles affects the heating efficiency of the reflow oven. This measuring method can be useful for monitoring the operation of the reflow oven, soldering failure prediction and measuring input parameters of thermal modeling.     

高效燃气热水器的实验研究和节能分析

介绍了研制的新型家用燃气热水器和热水炉（兼有热水供应和采暖的功能）其特点是：冷凝传热和低污染燃烧技术。对家用燃气热水器和热水炉进行了实验研究，在不同运行工况下测定了热水器的热效率和NOx及CO的排放量，并与传统热水器进行了对比分析。实验结果表明，新型家用燃气热水器及热水炉具有高热效率和低污染排放的特点，它能大大降低对环境的污染。     

我国热处理能源技术开发概况和结构调整设想

概要论述了国外热处理能源技术发展现状和国内热处理技术发展概况，重点阐述了国外天然气能源技术现状及发展趋势和我国天然气能源技术状况及应前景；同时探讨了我国热处理工业天然气能源技术开发应用预测及研究、开发热处理工业天然气应用的关键技术和关键设备，并提出了我国热处理工业调整能源结构的初步设想。     

Thermal performance of integrated collector storage solar water heater with corrugated absorber surface

An investigation is reported of the thermal performance of an integrated solar water heater with a corrugated absorber surface. The thermal performance of the rectangular collector/storage solar water heater depends significantly on the heat transfer rate between the absorber surface and the water, and on the amount of solar radiation incident on the absorber surface. In this investigation, the surface of the absorber is considered to be corrugated, with small indentation depths, instead of plane. The modified surface has a higher characteristic length for convective heat transfer from the absorber to the water, in addition to having more surface area exposed to solar radiation. The corrugated surface based solar water heater is determined to have a higher operating temperature for longer time than the plane surface. It means during the operation of water heater, more solar energy is converted into useful heat. However, this modification has reduces the efficiency of the system marginally.     

天然气热风炉在干燥行业中的节能应用

介绍了天然气直燃热风炉在干燥行业的节能应用。采用天然气直燃热风炉代替蒸汽换热装置,可大幅提高干燥系统的热效率,节能效果显著。通过对某生物制药公司干燥系统的改造实践,取得了比较满意的改造效果。改造后,干燥介质温度可达到180℃以上,出力稳定,使设备生产能力提高20%。另外,干燥介质的温度可以根据生物质饲料所含水分自动调节,确保了干燥品质。系统热效率由改造前的44%提高到96%以上。     

Experimental study on titanium heat exchanger used in a gas fired water heater for latent heat recovery

In general, latent heat recovery is usually accompanied by the corrosion of the heat exchanger, which is caused by the strongly acidic condensate when the temperature of the flue gas is lowered below the acid dew point. The present study has been conducted to investigate the heat and mass transfer characteristics in a titanium heat exchanger with excellent corrosion resistance used for waste heat recovery with the condensation arranged in a gas fired water heater. In addition, the thermal efficiency of the gas fired water heater was evaluated based on the net calorific value at the maximum rated output during latent heat recovery from the exhaust flue gas. Parametric studies were conducted for the flue gas flow rate, inlet temperature and mass flow rate of the supplied water, respectively. Different arrangements of the tubes of the heat exchanger including in-line and staggered configurations were investigated. The experimental results indicate that the thermal efficiency of the gas fired water heater with a latent heat recovery (LHR) heat exchanger was enhanced by about 10% compared with conventional instantaneous water heaters, i.e., water heaters without heat recovery. In addition, in terms of the Nusselt number and the Sherwood number, the heat and mass transfer performance of the staggered tube bank type were approximately 50% and 10% higher than that on the in-line tube bank type when the Reynolds number of the flue gas was 10³.     

提高YJP-Q系列车用液体加热器热效率的试验研究

为提高车用液体加热器的热效率,设计了双水腔换热器和双面燃气加热换热器。经台架试验,二者的热效率比原机有大幅提高,而排气温度大幅下降;还对燃烧室燃气回流罩位置及水流量对加热器热效率的影响进行了试验研究。