地埋管地源热泵复合蓄能系统方案可行性分析

根据办公楼所在的武汉地区气候特点及水文地质状况,在满足建筑物房间供冷供热要求的同时,采用地埋管地源热泵蓄能复合式空调系统,并利用消防水池作为水蓄冷装置。采用蓄冷优先的控制策略,能充分利用谷段电力,由蓄冷量满足尽可能多的冷负荷,不足部分由冷水机组直接供冷,可提高空调系统的运行效率,降低运行费用。经过方案的对比分析表明,该办公楼实施地埋管地源热泵中央空调蓄冷(热)项目,虽增加了投资成本,比常规空调系统在每年运行费用却可节约34.75万元,节能效率为78.6%,节能效果好,6年左右可收回高出的初投资。因而,从经济和技术的角度来说,该办公楼应用地埋管地源热泵复合式系统是可行的,运行费用低,社会经济效益显著,符合国家节能减排和可持续发展政策。     

浅谈高层建筑消防水池容量设计

在设计工作中,有人认为消防水池容量越大越好、越安全、这种观点是片面的。超规范设置谈不上经济合理,水质也难以保证,何以"安全适用"?建筑消防水池的储水量需要设计多大,才能做到既能满足火灾时消防用水量的要求,又能达到科学、经济、节省投资的目的,本文对当前实际工程中消防水池储水量的设计情况,以规范为指导,因地制宜综合考虑消防水量对建筑消防水池的储水量设计作进一步的探讨。     

武汉泛海城市广场一期商业综合体水蓄冷动态模拟

武汉泛海城市广场一期利用分时电价及消防水池,采用水蓄冷空调系统可达到移峰填谷、提高电网安全运行,降低用户运行费用的目的,同时满足项目LEED论证条款要求。项目的显著特点是商业综合体消防水池容积1600m3,水深8m,消防水池容积大,水位深,蓄冷量大;同时因消防水池深,在水池中间设内撑梁,通过动态模拟的方法分析了结构内撑梁对斜温层产生的影响。     

浅谈建筑工程中消防水池漏水修补措施

本文以某工程地下室消防水池修补全过程,从施工技术上分析了消防水池漏水的修补措施,值得参考。     

大唐商城消防水池蓄冷

本文介绍了某商城中央空调工程利用消防水池蓄冷的设计和施工方法以及运行效果,讨论了利用消防水池蓄冷的特点和运行方式.     

土壤特性对土壤源热泵系统影响测试分析

通过介绍土壤源热泵系统的工作原理,体现土壤源热泵系统的优势,指出土壤特性对土壤源热泵系统的重要性,给出土壤特性参数的测试方法,通过模拟测试土壤热导率和初始温度对土壤源热泵系统的影响,并运用实测验证土壤热导率和初始温度影响土壤源热泵系统的性能,为地源热泵系统在国内的推广应用提供一定的参考。     

基于全年热平衡的混合式地源热泵运行特性的实验研究

通过实验分析得出混合式地源热泵在工程应用中的意义。指出合理的混合式地源热泵冷却塔与地埋管的连接方式,在综合考虑地源热泵地埋管全年吸热排热平衡与地源热泵系统效率的基础上得出混合式地源热泵的合理控制方式和控制参数。指出地埋管单位井深换热量无明确的意义,提出地埋管单位井、地埋管内换热介质与土壤原始温度单位温差换热量的意义,并在本实验中给出地源热泵机组制冷效率与地埋管出口水温的关系。     

地源热泵在广东地区空调工程中应用可行性分析

分析计算了广州市自然气候环境、土壤状况和介质温度,对多种形式的地源热泵空调系统在广东地区应用的条件和可行性进行了分析,提出单一地源热泵空调技术并不适合广东地区使用,广东地区应因地制宜开展地源热泵空调组合技术研究.     

地埋管地源热泵系统设计及其经济性分析

对地埋管地源热泵系统换热器的出口温度进行了计算分析;介绍了压缩机匹配和辅助系统的设计,并对地源热泵系统的经济性进行了简要的分析。     

运行时间机制对医院建筑地埋管地源热泵系统的影响

通过DEST软件模拟出医院住院部全年动态负荷情况,分析了医院建筑负荷的特点.建立土壤源热泵系统地埋管换热物理和数学模型,以FLUENT为分析工具,对该建筑的地源热泵系统进行以运行时间为变量的数值计算分析,得到不同运行时间下的地温和管内流体的温度分布规律.以间歇运行时间为变量,得到辅助冷却模式下地温和管内流体的温度分布规律,提出了医院建筑地埋管地源热泵系统的优化运行模式.     

Effect of ignition condition on typical polymer's melt flow flammability

Polymer's melt flow behavior has triggered great interest due to the mutual-enhancing loop effect between vertical polymer fire and the induced flowing pool fire. The aim of the study was to quantitatively investigate the effect of ignition conditions on the polymer's melt flow flammability. Polypropylene (PP) sheets with a thickness of 4mm were selected as the test samples. An experimental rig was designed to study the interaction between the vertical PP sheet fire and the corresponding pool fire. Ignition was achieved at three locations, i.e. the lower right corner, the lower middle edge, and the whole lower edge of the PP sheets. All tests were conducted in an ISO9705 fire test room. Heat release rate, smoke temperature and other common parameters in fire hazard analysis were measured with the help of the fire room facilities. Results indicated that ignition conditions evidently impact on heat release rate development, peak heat release rate, smoke temperature, smoke generation and smoke toxicity. Furthermore, these experimental results preliminarily demonstrated the feasibility of the designed setup in studying interaction between vertical polymer sheet fire and the induced pool fire, although further modification may be needed.     

隧道火灾中正庚烷池火燃烧特性的实验研究

隧道火灾中热释放速率是评估临界风速、最高温度及温度分布的一个重要参数,而火源高度和隧道宽度是两个影响热释放速率的重要因素。为揭示上述两个因素对隧道火灾发展的影响,在缩放比例为1:10的隧道模型中进行了一系列小尺寸火灾模拟实验并对正庚烷池火的燃烧过程进行了研究。结果表明:隧道火灾的热释放速率明显大于开放环境,其燃烧过程可分为初始燃烧阶段、过渡阶段和稳定燃烧阶段;增加火源高度地面火灾（火源高度与隧道高度之比H*=0.1）质量燃烧速率小于其他各工况,H*=0.7时质量燃烧速率能增大到地面火灾的3.53倍~5倍;无量纲火焰蔓延总长度正比于无量纲热释放速率的五分之二次方,由于隧道侧壁的限制作用,其比例系数小于Hasemi's模型。     

低温热泵用涡旋压缩机性能的试验研究

制定低温热泵用涡旋压缩机试验方案,对研制的原型机进行性能测试。试验结果表明：在冷凝温度不变的情况下,随着蒸发温度的降低,原型机的制热量有所减少,但减少的速度低于普通热泵系统用涡旋压缩机;压缩机的电功率有所增加,但增加的幅度不大,且压缩机的排气温度也有所降低,故在低温工况下采用准二级压缩热泵用涡旋压缩机比采用普通热泵用涡旋压缩机可以更有效地提高空气源热泵的低温制热性能,是寒冷地区用小型空气源热泵比较适宜采用的压缩机。     

Keys to modeling LNG spills on water

Although no LNG ship has experienced a loss of containment in over 40 years of shipping, it is important for risk management planning to understand the predicted consequences of a spill. A key parameter in assessing the impact of an LNG spill is the pool size. LNG spills onto water generally result in larger pools than land spills because they are unconfined. Modeling of LNG spills onto water is much more difficult than for land spills because the phenomena are more complex and the experimental basis is more limited.

The most prevalent practice in predicting pool sizes is to treat the release as instantaneous or constant-rate, and to calculate the pool size using an empirical evaporation or burn rate. The evaporation or burn rate is particularly difficult to estimate for LNG spills on water, because the available data are so limited, scattered, and difficult to extrapolate to the large releases of interest.

A more effective modeling of possible spills of LNG onto water calculates, rather than estimating, the evaporation or burn rate. The keys to this approach are to:

• Use rigorous multicomponent physical properties.

• Use a time-varying analysis of spill and evaporation.

• Use a material and energy balance approach.

• Estimate the heat transfer from water to LNG in a way that reflects the turbulence.

These keys are explained and demonstrated by predictions of a model that incorporates these features. The major challenges are describing the effects of the LNG–water turbulence and the heat transfer from the pool fire to the underlying LNG pool. The model includes a fundamentally based framework for these terms, and the current formulation is based on some of the largest tests to-date. The heat transfer coefficient between the water and LNG is obtained by applying a “turbulence factor” to the value from correlations for quiescent film and transition boiling. The turbulence factor is based on two of the largest unignited tests on water to-date. The heat transfer from the fire to the pool is based on the burning rate for the largest pool fire test on land to-date.     

双效溴化锂吸收式热泵余热回收系统数值模拟研究

溴化锂吸收式热泵机组可以有效回收利用工业和建筑中的各种形式低温余热,提高余热资源回收率,但设备参数对热泵性能影响很大。因此本文基于温度对口和梯级利用的原则,对蒸汽型双效溴化锂吸收式热泵机组内传热部件进行热力及传热分析,通过质量和能量守恒建立热泵机组数学模型,分析热网供水温度、蒸发器进口低温余热水温度和驱动热源温度这三个外部因素的变化对系统性能的影响。研究结果表明:热网供水温度在49℃左右,热泵系统COP最佳为2.67;蒸发器进口低温余热水温度在47℃左右时,热泵系统COP最佳为2.67;随着驱动热源温度的上升,热泵系统的COP呈上升趋势。为吸收式热泵实际运行过程中,合理设置设备参数提高热泵性能提供指导。     

换热因素对空气源热泵热水器压缩机运行范围影响探讨

简要分析空气源热泵热水器系统运行对压缩机运行范围的影响,由于换热特性和热泵系统热力特性的限制,在低温运行条件下,冷凝温度将不超过65℃;而提高压缩机蒸发温度上限的措施,仍然不能免除在夏季运行采取防止蒸发温度过高的措施.在技术措施正确的前提下,空调压缩机可以满足空气源热泵热水器的应用要求.本文指出,我国标准中规定20℃为空气源热泵热水器额定运行进风温度是不合理的,客观上对行业发展产生了不良影响;目前市场上存在的产品质量问题,主要原因是受标准的影响和系统设计的技术措施不当,并非压缩机性能问题.     

风冷热泵结霜工况下的实验研究

对一台风冷热泵室进行了结霜工况下的实验测试,实验地研究了风冷热泵在规定的环境温度下制热能力、出风温度以及热泵制热性能的变化。实验结果表明热泵结霜严重的影响TSU热能力、出风温度已经热泵制热性能,研究结论对热泵系统设计具有重要的参考价值。     

Investigation of R-744 Voorhees transcritical heat pump system

Using economizer in R-744 heat pump cycle is an effective way to improve the heating capacity in cold climates. In this paper, a modification construction of reciprocating compressor with economizer port, a Voorhees compressor was introduced and the heat pump cycle with Voorhees economizer was compared with the traditional screw or scroll economizer cycles. Both the R-744 transcritical heat pumps with and without Voorhees economizer were tested at the same conditions with different air mass flow rates and different evaporating temperatures. The results show that the heating capacity of the heat pump with Voorhees economizer can be two times higher than the transcritical heat pump without economizer at low evaporating temperature conditions. At the same capacity operation conditions, the efficiency of the heat pump with Voorhees economizer is higher at high refrigerant mass flow rate conditions. The optimum discharge pressure of the heat pump with Voorhees economizer is found to be higher than the heat pump without economizer at the same ambient conditions. For mobile heat pump application, CO₂ transcritical heat pump with Voorhees economizer demonstrates better performance comparing to the conventional transcritical CO₂ heat pump without economizer when the evaporating temperature is lower than −20 °C, or when the mobile is idling with low compressor RPM.     

湖水源热泵冬季供暖适应性研究

从湖体水温、热泵机组能效、冷排水对水环境的影响及热泵系统节能性四个方面分析了湖水源热泵在冬季供暖的适应性。研究表明,湖水源热泵供暖技术具有良好的节能效益,实测热泵机组能效达到4.34～4.81,相对传统的风冷热泵、电锅炉、燃气锅炉系统而言,水源热泵系统的节能率分别达到5%、68%和29.8%。     

Temperature distribution in steel frames exposed to a fire environment

Abstract

A theoretical model and a solution scheme for studying the temperature distribution in steel structures exposed to a prescribed fire environment are presented. Radiation and convection as well as conduction of heat are taken into consideration. The method of orthogonal collocation is employed for the solution. Efficiency of the method as applied to the problem is demonstrated. Temperature distributions in rigid frames exposed to the fire environment specified by ASTM standard curve are examined. It is found that the temperature increases rapidly only in regions surrounding the fire loads. No appreciable temperature change takes place elsewhere in the structures. The effect of the fire environment is essentially local to the heat source. The methodology described herein is useful for the quantitative assessment of the fire resistance of structures.