土壤热交换量的计算及其变化

本文利用北京等六个热量平衡观测站三年观测资料,计算和分析了土壤热交换量的日变化、年变化及其空间变化特征。最后还分析了几种土壤热交换量的经验计算方法。

秦岭黄淮平原交界带地表面热量平衡的计算和分析（下）———土壤热交换量和乱流热交换量的计算和分析

采用适合于交界带自然地理特点、计算精度较高的地温曲线图解法、温度变化相关法和余项法，计算了交界带的土壤热交换量和乱流热交换量，分析其水平、垂直分布和季节变化的特点。

等风机功耗下不同构型全热换热器的性能比较

薄膜式全热换热器的通道构型对其性能有重要影响,为改进全热换热器的性能以达到更好的节能效果,研究分析了几种通道结构的流动及传递特性,采用数值模拟方法,在等风机功率下对不同通道构型的全热换热器的性能进行了预测和比较．

蒸发式冷凝器用于人防工程采暖的可行性研究

蒸发式冷凝器的夏季工况是一个既有热量传递又有质量传递的过程,在夏季运行时稳定、可靠。但把蒸发式冷凝器转换为蒸发器的冬季工况,由于蒸发式冷凝器换热管为光管以及喷淋水量有限,结构本身的特性决定了采暖工况的能效比(EER)小于1,这种转换没有实际的意义,也不经济。

土壤源热泵工程在地温异常情况下的解决方案

本文首先介绍了土壤源热泵的工作原理,然后通过某具体工程实例分析了施工区域地温异常的情况,最后指出了由于地温异常所带来的问题以及该问题的解决方案。本文可以为土壤源热泵系统在特殊状况下的设计提供参考。

龙头桥水库工程对局地气候的影响

近年来随着对环境问题的重视,对可持续发展的重视,人们已经认识到:水资源开发建设工程对环境影响既存在有利的一面,也存在不利的一面,必须全面分析、正确评价。随着我国社会经济的增长,科学技术的进步,水利工程做为我国的基础设施建设,国家也逐步加大对水利工程和科研项目的投资,从一些实践经验得出的理论也逐渐成熟。龙头桥水库是黑龙江省2002年建成并投入使用的一个大型水利控制性工程,主要以防洪、灌溉为主,除了这些它又存在着很大的潜在社会经济效益,同时也对周边的环境产生一些不利影响,文章利用实践经验分析了龙头桥水库工程对局地气候的影响。

蒸汽煅烧炉换热系统能力提升

对蒸汽煅烧炉进行改造,通过增大蒸汽煅烧炉换热面积,增加蒸汽煅烧炉蒸汽进汽量,提升蒸汽煅烧炉热交换能力,提升单台蒸汽煅烧炉的生产能力。

外推法原理的深入理解

分析了学生对外推法散热修正原理深入理解的困难所在,将另一种散热修正法(即冷热补偿法)的思想方法运用其中来深入分析,解释了外推法原理的合理性,帮助学生更深更好地理解外推法散热修正的原理。

提高立式高效冷却器冷却效果的研究

针对立式高效冷却器排水口偏低,实际换热面积较理论换热面积小,冷却效果相对较差的问题,提出一种有效增大实际换热面积从而提高冷却效果的方法。该方法将冷却水排水口的位置设计到冷却器壳程的最高点,增大实际换热面积来达到提高冷却效果的目的。

Experimental Research on Flow Maldistribution in Plate-Fin Heat Exchangers

The flow maldistribution and the effect of different inlet configuration on the flow distribution in platefin heat exchangers were studied experimentally. It is found that the flow maldistribution is serious because of the defects of inlet configurations, while the inlet configuration and Reynolds number are the main factors affecting the flow distribution. The improved inlet configurations, which are the header with a two-stage distributing configuration and the guide vane with a fluid complementary cavity were proposed and tested in this paper. The experimental results show that the improved inlet configurations can effectively improve the performance of flow distribution in heat exchangers.

Synthesis and adsorption property of zeolite FAU/LTA from lithium slag with utilization of mother liquid

Co-crystalline zeolite FAU/LTA-0 was synthesized by hydrothermal method from lithium slag. To make the most of excess silicon and alkali sources in mother liquid derived from FAU/LTA-0, zeolite FAU/LTA-I b was synthesized in the same method with the use of mother liquid by adding a certain amount of aluminum source. Influences of different adding ways of aluminum source and recycling dosages of mother liquid on synthesis of zeolites FALl/ LTA with mother liquid were investigated. The phase, microstructure and thermostability of FAU/LTA-0 and FAU/LTA-lb were characterized by XRD, SEM and TG-DTA. The calcium and magnesium cation exchange capacities （CECs） of the zeolites were determined. The results have shown that co-crystalline zeolite can be synthesized with the use of mother liquid by adding aluminum source after 2 h of reaction. Compared with FAU/LTA-0, the crystal twinning structure of FAU/LTA-lb became weaker, the grain size was smaller, and the thermostability was better. With a lower dosage of mother liquid, the content of P-type impurity in product decreased significantly, and the content of LTA phase increased. The reuse rate of mother liquid can reach 48%. The CECs of FAU/LTA-I b-150 can reach 343 mg CaCO3. g-1 and 180 mg MgC03. g-1, showing more excellent adsorption capacities than FAU/LTA-0 and commercial zeolite 4A. The full recycling use of mother liquid to synthesize zeolite FAU/LTA which can be applied for detergent not only improves resource utilization but also reduces oroduction cost.

Synthesis of Flexible Heat Exchanger Networks with Stream Splits Based on Rangers of Stream Supply Temperatures and Heat Capacity Flowrates

A new superstructure model of heat exchanger networks (HEN) with streamsplits based on rangers of streams supply temperatures and heat capacity flow rates is presented.The simultaneous optimal mathematical model of flexible HEN synthesis is established too. Firstly,the streams with rangers of supply temperatures and/or the streams with the rangers of heat capacityflow rates are pretreated; Secondly, several rules are proposed to establish the superstructuremodel of HEN with splits and the simultaneous optimal mathematical model of flexible HEN; Thirdly,the improving genetic algorithm is applied to solve the mathematical model established at the secondstep effectively, and the original optimal structure of HEN based on the maximum operation limitingcondition can be obtained easily; Finally, the rules of heat exchange unit merged and the heat loadof heat exchanger relaxed are presented, the flexible configuration of HEN satisfied the operationcondition between the upper and down bounds of supply temperature and heat capacity flow rates canbe obtained based on the original optimal structure of HEN by means of these rules. A case studydemonstrates the method presented in this paper is effective

Selection of organic Rankine cycle working fluid based on unit-heat-exchange-area net power

To improve energy conversion efficiency, optimization of the working fluids in organic Rankine cycles(ORCs) was explored in the range of low-temperature heat sources. The concept of unit-heat-exchange-area(UHEA) net power, embodying the cost/performance ratio of an ORC system, was proposed as a new indicator to judge the suitability of ORC working fluids on a given condition. The heat exchange area was computed by an improved evaporator model without fixing the minimum temperature difference between working fluid and hot fluid, and the flow pattern transition during heat exchange was also taken into account. The maximum UHEA net powers obtained show that dry organic fluids are more suitable for ORCs than wet organic fluids to recover low-temperature heat. The organic fluid 1-butene is recommended if the inlet temperature of hot fluid is 353.15-363.15 K or443.15-453.15 K, heptane is more suitable at 373.15-423.15 K, and R245 ca is a good option at 483.15-503.15 K.

Analyzing Heat Extraction and Sustainability of EGS with a Novel Model

We investigate the subsurface heat exchange process in EGS （enhanced geothermal systems） with a previously developed novel model. This model treats the porous heat reservoir as an equivalent porous medium of a single porosity. However, it considers local thermal non-equilibrium between solid rock matrix and fluid flowing in the factures and employs two energy conservation equations to describe heat transfer in the rock matrix and in the fractures, respectively, enabling the modeling and analyses of convective heat exchange in the heat reservoir. Another salient feature of this model is its capability of simulating the complete subsurface heat exchange process in EGS. The EGS subsurface geometry of interest physically consists of multiple domains： open channels for injection and production wells, the artificial heat reservoir, and the rocks enclosing the heat reservoir, while computationally we treat it as a single-domain of multiple sub-regions associated with different sets of characteristic properties （porosity and permeability, etc.）. This circumvents typical difficulties about matching boundary conditions between sub-domains in traditional multi-domain approaches and facilitates numerical implementation and simulation of the complete subsurface heat exchange process. This model is used to perform a comprehensive parametric study with respect to an imaginary doublet EGS. Effects of several parameters, including the permeability of heat reservoir, heat exchange coefficient in the heat reservoir, the specific area of fractures in the heat reservoir, and thermal compensation from surrounding rocks, on the heat extraction efficiency and EGS lifetime are analyzed.

Thermal Response Test for Kelix GHE System

The performance of a BTES （borehole thermal energy storage） system is primarily governed by ground heat flux, soil thermal properties and groundwater conditions. However, the design of the heat exchanger used within the BTES system can also make a significant difference in the efficiency of the system. A thermal response test was carded out for a Kelix GHE （ground heat exchanger） system, the latest innovation in geothermal ground loop construction, on an Ecofarm in the town of Caledon East, Ontario, Canada. In addition, a verifying test was performed for a CEES （conventional earth energy system） located 6 m away from the Kelix GHE. The boreholes for these two different heat exchanger designs were drilled with the same diameter, to the same depth and were located in the same/identical geo-hydrological conditions. The response test provided the effective average of undisturbed ground temperature, geothermal properties including thermal conductivity, heat capacity and thermal resistance between the fluid and the borehole wall. The mathematical analysis method used for the response test is presented here. Results of the response test were verified, analyzed and are further discussed.

Study of Total Process Energy Integration

The energy utilization consistency method in process integration extracts the key component of process energy utilization, and simplifies the procedure of process analysis and integration. The method allows the conversion of the total process energy integration into a synthesis problem of a pseudo-heat exchanger network. The advantages of using the energy utilization consistency and the pseudo-temperature methods are presented by two examples of integration of large-scale complex processes. The improved genetic algorithm is proved to be an effective tool in the retrofitting procedures.

Combined mass and heat exchange network synthesis based on stage-wise superstructure model

Integrating multiple systems into one has become an important trend in Process Systems Engineering research field since there is strong demand from the modern industries. In this study, a stage-wise superstructurebased method is proposed to synthesize a combined mass and heat exchange network(CM&HEN) which has two parts as the mass exchange network(MEN) and heat exchange network(HEN) involved. To express the possible heat exchange requirements resulted from mass exchange operations, a so called "indistinct HEN superstructure(IHS)", which can contain the all potential matches between streams, is constructed at first. Then, a non-linear programming(NLP) mathematical model is established for the simultaneous synthesis and optimization of networks. Therein, the interaction between mass exchange and heat exchange is modeling formulated.The NLP model has later been examined using an example from literature, and the effectiveness of the proposed method has been demonstrated with the results.

Characterization of Thailand Rice Husk Ash from Biomass Power Plant and Synthesized Zeolite

Thailand rice husk ash was used to synthesize zeolite by hydrothermal treatment. Raw rice husk ash material and zeolitic products were characterized in terms of specific surface area （BET method）, morphological analysis （SEM）, mineralogical composition （XRD） and CEC （cation exchange capacity）. LOI （Loss of ignition） of rice husk ash was also evaluated. Result indicated that the rice husk ash sample from Roi-Et Green power plant in the Northeastern of Thailand with combustion temperature of 650 ℃ has a high content of SiO2 （above 90 wt.%）. Zeolite-X from rice husk ash with high content of Si was successfully synthesized using hydrothermal treatment. The zeolitic material synthesized with the optimal condition possessed a maximum value of CEC of 503 meq/100g, and it has potentiality to be used as ion exchangers.

A Numerical Model of a U-Tube Vertical Ground Heat Exchanger Used as an Evaporator

The paper presents a general distributed model of a vertical U-tube direct expansion heat exchanger coupled with the ground. This model is developed for studying the dynamic thermal behavior of a buried heat exchanger which is an integral part of a so-called direct expansion heat pump. The transient conservative equations of mass, momentum and energy considering single and two-phase flow of refrigerant are derived and presented. The diffusive heat exchange with the ground is treated using an analytical approach to treat short-time scale response of vertical boreholes based on an imposed temperature. The thermal interference between the two pipes of the heat exchanger is also considered. The mathematical equations of the model are numerically presented using a control volume formulation and the solution of the system of equations is obtained by successive iterations. The dynamic behavior of the evaporator is simulated and the numerical results are analyzed regarding spatial parameters distribution and thermal interference influence.

通道构型对全热换热器性能的影响

薄膜式全热换热器的通道构型对其性能有重要影响,为改进全热换热器的性能以达到更好的节能效果,研究分析了几种通道结构的流动及热质传递特性,采用数值模拟方法对不同通道构型下全热换热器的性能进行了预测及比较分析。结果表明:正三角形通道全热换热器各项性能指标均最差;对于矩形通道,随着长宽比的增加,显热效率、焓效率及全热交换量变化不大,而压降减小更迅速,导致换热器整体性能有所提高;近无限大平板通道全热换热器各项性能指标均为最佳。结论是通道支撑越少,全热换热器性能越好。