共查询到20条相似文献,搜索用时 171 毫秒
1.
2.
以热力学为指导,通过利用高效的传热技术与吸收式热泵技术的耦合,对低位烟气余热“质”和“量”分控回收,可实现低位烟气余热的深度回收与梯级利用.应用于高水蒸气含量的燃油、燃气设备的烟气余热回收,不仅回收显热,还深度回收其潜热,综合效益最佳.高效的传热技术可减小余热与利用介质间的传热温差而减少传热过程的不可逆损失是最为核心的技术问题,对其进行分析探讨,有利于高效、节能、环保的低位烟气余热深度回收与利用技术的发展. 相似文献
3.
4.
燃气锅炉排烟冷凝热回收技术 总被引:4,自引:2,他引:2
通过对天然气烟气特性的分析以及对冷凝式锅炉热效率的分析和计算得出,将烟气温度降低到露点温度以下对烟气进行余热回收有重要的实际意义;冷凝式换热器就是增设在天然气锅炉尾部的余热回收装置,可以将排烟中大量的能量加以回收利用,从而达到节能环保的效果.对几种不同结构型式的冷凝换热器的传热效果、烟气阻力以及腐蚀性等问题进行了定性对比,对各种排烟余热回收技术进行了综合探讨. 相似文献
5.
一、前言 加热炉是将燃料的化学能转化成热能的主要设备。由于其排烟温度一般较高,使得热损失偏大,直接影响加热炉的热效率。为了节约燃料消耗,提高加热炉的热效率,大多数厂家对烟气余热进行了回收。随着能源的紧张,烟气余热回收已显得日趋重要。 加热炉的余热最普遍的回收方式是利用烟气余热预热助燃空气。如图1所示的空气 相似文献
6.
加热炉烟气余热自回收的节能计算江西新余钢铁总厂罗晓青,杨三根加热炉炉膛排出的烟气温度比较高,烟气余热的利用,通常是先回收用于自身(如预热空气,国标GB3486(评价企业合理用热技术导则》中规定有工业炉烟气余热回收率的要求),然后进一步进行用于炉外回收... 相似文献
7.
根据油田注汽锅炉热平衡测算数据及结果分析,找出了其运行热效率低的原因。影响注汽锅炉运行热效率的主要因素是排烟温度和空气系数,测算分析表明,大部分注汽锅炉二者均超标。根据注汽锅炉特点提出了提高运行热效率的技术措施,即空气系数调节技术、化学清烟垢技术和烟气余热回收技术。工程应用表明,节能及经济效益显著。 相似文献
8.
9.
10.
11.
12.
针对钢铁生产流程中焦化及烧结工序的能量平衡、热效率及火用效率等展开研究,并对各种余热资源的能级等进行了计算和评价。在焦炉产生的余热资源中,红焦的焓值和火用值均高于其他两项,说明红焦余热量大,并且余热品质好。焦炉煤气的比焓值和比火用值均大于焦炉烟气,说明焦炉煤气的能量品质要好于焦炉烟气,而焦炉烟气的焓值大于焦炉煤气。烧结矿的比焓值和比火用值均比烧结烟气和环冷废气的比焓值和比火用值高,说明烧结矿的余热资源量和余热品质均高于烧结烟气和环冷废气。这项研究为焦化工序及烧结工序余热利用等奠定了基础。 相似文献
13.
介绍了Consteel电炉余热回收特点,并根据不同的温度和含尘研制了光管一翅片管一热管式余热锅炉,设计中充分考虑了结构合理、热稳定性好、检修维护方便,并给出现场测试数据与理论计算结果的对比,在Consteel电炉余热回收中使用光管一翅片管一热管式余热锅炉,既回收了烟气显热又减少环境污染,有着良好的推广前景。 相似文献
14.
Concentrating type solar cookers are expected to demonstrate high performance because of the large collection area employed. However, the net amount of heat used is still low. This is greatly attributed to the large amount of heat losses from the bare food pots used. Introducing the oven type concept as an alternative approach for collecting the concentrated solar energy would drastically boost the overall cooker efficiency. In this work, the transient heat balance equations were developed for predicting the thermal behavior of an oven type concentrating solar cooker. This simulation was used to show theoretically the great advantage of using a glass-sided oven over the conventional bare receiver pot. The resulting mathematical model was solved using numerical integration. The transient nature of solar radiation and effects of wind speed variation were all taken into consideration. The analysis showed that the oven type receiving pot has both a higher fluid temperature and overall receiver efficiency compared to the bare receiver type, working under similar conditions. 相似文献
15.
《International Journal of Hydrogen Energy》2019,44(48):26597-26608
This study proposes a heat release rate (HRR) estimation method for a carrier loaded with fuel cell vehicles (FCVs) trapped in a tunnel fire. The carrier is divided into several parts, and the HRR is estimated by adding the HRRs of all system parts (carrier and FCVs). The HRR of one FCV was compared with that of a gasoline vehicle. The thermal fume behavior in longitudinally inclined tunnel fires was also investigated. Even a modest inclination hastened the thermal fume propagation of the FCV fires. Of relevance to the prevention of tunnel fire disasters, the thermal fume behavior differed between FCV and gasoline fires. For safety assessment of tunnel fires, the thermal fume behaviors of an FCV fire and gasoline vehicle fire in a tunnel were investigated by the proposed method. In the case of no longitudinal inclination, the thermal fume of the FCV fire arrived earlier than that of the gasoline vehicle fire (by 1 min at x = 200 m and over 4 min at x = 250 m) because of the emitted hydrogen gas. At 2% longitudinal inclination, the thermal fume of the FCV fire propagated to the downstream side 4 min before that of the gasoline vehicle fire. At 4% longitudinal inclination, the thermal fume propagated 50 m downstream of the initial fire after 10 min. Therefore, after the hydrogen emission, the thermal fume of the FCV fire traveled faster than that of the gasoline vehicle fire. The proposed HRR estimation method can contribute to the risk analysis of various types of tunnel fires. 相似文献
16.
通过对某镀锌厂生产线的供用能设备进行全面的热平衡测试及分析,提出对退火炉烟气余热回收利用,以代替现有供热锅炉方案。本方案已实施并达到预期效果。 相似文献
17.
M.A.H. Mamun M.M. Rahman M.M. Billah R. Saidur 《International Communications in Heat and Mass Transfer》2010
The present work is aimed to study mixed convection heat transfer characteristics within a ventilated square cavity having a heated hollow cylinder. The heated hollow cylinder is placed at the center of the cavity. In addition, the wall of the cavity is assumed to be adiabatic. Flows are imposed through the inlet at the bottom of the left wall and exited at the top of the right wall of the cavity. The present study simulates a practical system such as air-cooled electronic equipment with a heat component or an oven with heater. Emphasis is sited on the influences of the cylinder diameter and the thermal conductivity of the cylinder in the cavity. The consequent mathematical model is governed by the coupled equations of mass, momentum and energy and solved by employing Galerkin weighted residual method of finite element formulation. A wide range of pertinent parameters such as Reynolds number, Richardson number, cylinder diameter and the solid-fluid thermal conductivity ratio are considered in the present study. Various results such as the streamlines, isotherms, heat transfer rates in terms of the average Nusselt number and average fluid temperature in the cavity are presented for different aforesaid parameters. It is observed that the cylinder diameter has significant effect on both the flow and thermal fields but the solid-fluid thermal conductivity ratio has significant effect only on the thermal field. 相似文献
18.
A modular energy storing heat exchanger designed to use pentaerythritol for thermal storage (solid-solid phase change at 182°C) is tested in an oven by circulating heat transfer oil which is electrically heated in a manner to simulate a concentrating solar collector. Three efficiencies for heating the system under controlled and measured power input are determined—the heat exchanger efficiency, the efficiency of the heater with distribution lines, and the total system efficiency. Thermal energy retention times and cooking extraction times are determined, and along with the efficiencies, are compared with the results previously reported for a nonmodular heat exchanger. The modular configuration provides a highly improved extraction rate for cooking due to its wrap-around character and its increased surface-to-volume ratio. A full scale glass model of the copper tubing of the system is described and flow observations reported demonstrating how uniformly the parallel pumping branches perform and how trapped air pockets affect pumping power. A technique for measuring pumping power is described and its application to our system is quantified to show that less than 1 watt is required to circulate the heat transfer oil even when the system includes the solar collector and its longer connecting tubes. 相似文献
19.
M. A. Al-Nimr 《国际能源研究杂志》1998,22(2):161-168
A simple perturbation technique is used to reformulate the energy equations which describe the transient thermal behaviour of a radially lumped conjugated heat transfer problem in circular and parallel plate ducts of finite wall thickness. The simple perturbation technique is used to eliminate the coupling between the fluid and the solid-wall energy equations when the temperature difference between the fluid and the solid wall is a small perturbed quantity, which is true when the interface convective heat transfer coefficient between the fluid and the solid wall is high. A mathematical criterion is derived to determine the conditions under which fluid and solid wall are in thermal equilibrium. It is found that there are four dimensionless parameters that control the state of thermal equilibrium between the fluid and the solid domains. © 1998 by John Wiley & Sons, Ltd. 相似文献
20.
《Applied Thermal Engineering》2003,23(8):1005-1017
The melting temperatures of the palmitic acid (PA) (61.2 °C) and the myristic acid (MA) (52.2 °C) are high for solar thermal energy storage under the climate conditions of the some regions in Turkey. However, their melting temperatures can be adjusted to a suitable value by addition of MA to PA. In this study, the thermal analysis by differential scanning calorimetry technique shows that the mixture of MA and PA with 58.0 wt% MA forms a eutectic mixture with melting temperature of 42.6 °C and the latent heat of fusion of 169.7 J g−1. The melting temperature and latent heat of fusion of MA–PA eutectic mixture make it a suitable material for energy storage in passive solar space and greenhouse heating systems under the climate conditions of some residential and agricultural regions in Turkey. The present study also deals with the experimental establishment of thermal characteristics of the eutectic mixture as a phase change material in a vertical concentric two pipes––energy storage system. Reynolds and Stefan numbers were selected as experimental parameters and used for the evaluation of the results. The experimental results prove that the MA–PA eutectic mixture has attractive thermal characteristics during the melting and the solidification processes and it is a potential latent heat storage material for heating applications with respect to the climate requirements in Turkey. 相似文献