Swiss Federal Institute of Aquatic Science and Technology, Eawag, 8600 Dübendorf, Switzerland.
Water Res. 2014 Jan 1;48:548-58. doi: 10.1016/j.watres.2013.10.017. Epub 2013 Oct 17.
Raw wastewater contains considerable amounts of energy that can be recovered by means of a heat pump and a heat exchanger installed in the sewer. The technique is well established, and there are approximately 50 facilities in Switzerland, many of which have been successfully using this technique for years. The planning of new facilities requires predictions of the effect of heat recovery on the wastewater temperature in the sewer because altered wastewater temperatures may cause problems for the biological processes used in wastewater treatment plants and receiving waters. A mathematical model is presented that calculates the discharge in a sewer conduit and the spatial profiles and dynamics of the temperature in the wastewater, sewer headspace, pipe, and surrounding soil. The model was implemented in the simulation program TEMPEST and was used to evaluate measured time series of discharge and temperatures. It was found that the model adequately reproduces the measured data and that the temperature and thermal conductivity of the soil and the distance between the sewer pipe and undisturbed soil are the most sensitive model parameters. The temporary storage of heat in the pipe wall and the exchange of heat between wastewater and the pipe wall are the most important processes for heat transfer. The model can be used as a tool to determine the optimal site for heat recovery and the maximal amount of extractable heat.
未经处理的污水中含有大量能源，可以通过安装在污水管中的热泵和热交换器回收。该技术已经成熟，瑞士大约有 50 个设施，其中许多已经成功地使用了多年。规划新设施需要预测热回收对污水管中污水温度的影响，因为污水温度的改变可能会对污水处理厂和接收水的生物处理过程造成问题。本文提出了一种数学模型，该模型可以计算污水管中的排放以及污水、污水管空间剖面和周围土壤中的温度动态。该模型在 TEMPEST 模拟程序中得到了实现，并用于评估实测排放和温度时间序列。结果表明，该模型能够很好地再现实测数据，土壤的温度和导热率以及污水管与原状土之间的距离是模型最敏感的参数。管壁中的热量临时储存和污水与管壁之间的热量交换是传热的最重要过程。该模型可用作确定热回收最佳位置和可提取最大热量的工具。
