Heating load and COP optimisations for a universal steady flow endoreversible heat pump model

The heating load and coefficient of performance (COP) of a class of universal steady flow endoreversible heat pump cycle model, which consists of one heating branch, two cooling branches and two adiabatic branches, are optimised using the theory of finite time thermodynamics. The analytical formulae for heating load and COP versus temperature ratio as well as COP versus heating load of the cycle model are derived. Effects of the total heat exchanger inventory on performances of heat pump cycles are shown by detailed numerical examples. The results obtained herein include the optimal performances of endoreversible Otto, Brayton, Atkinson, Diesel, Dual and Carnot heat pump cycles.     

Cities under Siege: Urban Planning and the Threat of Infectious Disease

Many analysts argue that the potential for a natural, accidental, or nefarious infectious disease event to have a dramatic impact on urban areas in the United States and abroad is growing. After reviewing the justification for this position, this article considers what cities should do to prepare for a major disease event. Recognizing that prevention and preparation receive insufficient attention, we recommend that planners seek out and work with both public and private sector groups with roles in disaster planning; design land and transportation planning information systems to aid and support decision makers during crises; encourage greater self-sufficiency in food production and consumption; assist in the design of humane, realistic evacuation strategies and routes; and consider the effects of their day-to-day recommendations on disease risk and response.     

Implementation constraints in social enterprise and community Public Private Partnerships

Public Private Partnership (PPP) employs private sector expertise and skill to provide public goods and services. We examine three community PPP projects to identify critical success factors of the project outcomes. Two conclusions particularly stand out: first, the project must be aligned with both the public and private parties' business and service plans, and second, appropriate management structures and procedures must be established for obtaining this alignment. The latter effect recognizes the need to implement appropriate project governance practices including management discipline and expertise. We investigate these ideas further and present specific guidelines for PPP project design and implementation.     

A case study in early urban design: Toronto, 1966–1978

ABSTRACT

This is a study in the practice of postwar urban design in Toronto, Canada, based on archival documents and interviews with participants. The narrative begins with the hiring of one British-trained architect/urban designer, Raymond Spaxman, by the City of Toronto Planning Board in 1966. Spaxman then set up a new division of staff that he filled with five or six other architect/urban designers of various national and institutional origins. The study describes the work carried out by these urban designers, identifies the principle themes apparent in it, and relates this to published literature on the founding principles of postwar urban design. In most ways, the study's findings fit the current understanding of the early discipline – concern for pedestrians, sympathy for historical preservation – but in others not – it was different from but not antagonistic towards planning. The findings are then considered as an example of the international transfer of postwar planning ideas. The process of idea transfer in this case looks to have been more chaotic, and less definable, than existing paradigms suggest, but this might have been fairly common in second-rank, immigrant-receiving cities.     

辐射热源法检测卷材地板燃烧性能的探讨

在辐射热源法检测卷材地板的过程中,一些因素对检测结果的影响较大,会直接影响到符合性的判定。本文在笔者数年卷材地板燃烧性能的检测基础上,对几个影响卷材地板燃烧性能测定结果的因素进行了分析探讨,并对个别因素的影响程度进行了试验论证,为各位试验人员提供一个借鉴。     

塑性收缩对预拌混凝土的影响及控制措施

混凝土塑性收缩是预拌混凝土的质量通病,由于发生在混凝土硬化之前,容易被人忽视,而塑性收缩产生的裂缝将影响到混凝土结构的使用功能,轻者会有外观缺陷,重者导致楼板渗水。本文从塑性收缩产生原因、影响因素和控制措施几方面论述,以预防或减少塑性收缩对混凝土的危害。     

单桩竖向抗拔静载试验可行性分析

单桩竖向抗拔静载试验的主要目的是检测桩的单桩竖向抗拔承载力。为保证试验实施的可行性,在进行现场试验前需要对地基土反力、钢筋拉力以及钢筋焊接强度、管桩混凝土填芯长度等各种因素综合考虑和验算。     

拉萨市供暖技术的适宜性分析

充分考虑拉萨市太阳能资源丰富、矿物能源匮乏和生态环境脆弱等特点,通过对气候条件、能源供应情况、建筑特征和热负荷特性等要素的分析,对拉萨市利用天然气、电力等常规能源的各种供暖方案进行了分析对比,结果表明:城市集中供暖和大规模的区域集中供暖不适宜在拉萨采用,而应采用分散式或楼栋式供暖系统形式.合理的供暖方案既能满足人们对室内热舒适环境的需求,又有利于降低能源的消耗和污染物的排放,保护拉萨的生态环境.     

夏热冬冷地区住宅供暖问题刍议

夏热冬冷地区住宅供暖关乎人民健康,惠及民生,是我国实现小康目标的重要环节。集中供暖是供暖技术的一种形式,但若在夏热冬冷地区全面推广集中供暖,既无条件,也不现实,供暖技术应该多元化。提出了改进房间空调器、改善围护结构保温等技术措施,以及基于水源热泵的能源总线系统和热电联产耦合热泵的高能效集中供暖系统;指出了节能、转移和利用可再生能源等解决供暖能源的途径。     

独栋住宅土壤源热泵系统冬季供暖实证研究

本文以1栋上海地区独栋住宅为对象,对土壤源热泵系统冬季供暖性能和能效进行了实证研究.通过对系统运行参数的连续监测,实证了地埋管换热器每米埋管取热量、机组与系统的COP及系统节能率等指标.结果表明:地埋管换热器出水温度及循环温差较为稳定,埋管换热量为27 ～ 32 W/m;系统能效受部分负荷率影响较大,整个测试期系统COP在3.3～3.9之间;在满足同等舒适性条件下,土壤源热泵系统比空气源热泵节能31.0％,节能效果明显.