消除城市热岛效应的大尺度热管理技术

随着当前城市化进程的加快,人口、城市建筑群落的密集化,以及急剧增长的机动车数量,使得城市热岛效应日趋严重。与此同时,为维持人居环境的舒适性,室内制冷设备加速运转,废热废气大量排出,这不仅造成能源的极大消耗,也加重了环境的负担。本文深入剖析了这一严峻现实,探讨利用传热学、建筑学、地球工程学、城市规划学等理论,从整体着手发展宏观大尺度城市热管理技术,即引入城市冷却系统的概念。相对于传统的分户空调,城市冷却系统能够实现大范围的温度调节,从整体上给热岛降温,同时解决分户空调带来的能源过度消耗问题,从而提升总能利用效率。分析了城市热岛和建筑耗能现状,阐述了城市冷却系统的基本特征,集中评述了当前实现宏观大尺度城市冷却系统的典型技术手段,并提炼出了有待解决的一些关键问题。所探讨的城市冷却系统可为国家环境战略和能源战略的实施提供一定的参考。

Feasibility Study on Large Scale Thermal Management Strategy to Eliminate the Urban Heat Island Effect

With the urbanization process, and the increase of population density and building density, as well as heavy traffic of vehicles, the urban heat island effect becomes a more and more serious issue. Meanwhile, in order to maintain a comfortable living environment, tremendous indoor refrigerators are at work, which discharge a large quantity of waste heat and gas, involving not only large energy consumption, but also a heavy burden on the environment. In this paper, such problems are carefully analyzed. It is shown that one of the key technical strategies towards solving such problems lies in developing large-scale urban thermal management technologies with due consideration of heat transfer, architecture, geo-engineering, and urban planning. The concept of urban cooling system is proposed. Compared to the traditional household air-conditioning system, the new strategy is dedicated to cool down the whole hot city in a system level, which would better solve the problem of huge energy consumption, as well as improve the energy utilization efficiency of the whole city. The current situation of urban heat island and building energy consumption is reviewed, and the basic features of the urban cooling system are described. Typical technical approaches to realize the cooling system are evaluated and some key issues that remain to be solved are pointed out. The city cooling system as discussed in this paper can give some food for thought in working out a national environmental and energy development strategy.