Analysis of heat transfer in a helically coiled cooler of a mechatronic sample conditioning system

A mechatronic sample conditioning system requires a high degree of process automation. Special attention is to be paid to the cooling of a sample and maintaining its temperature and pressure. Therefore, the study of thermal performance of the sample cooler (heat exchanger) is an important step in the development of a sample conditioning system. The helically coiled sample cooler, highly efficient, compact and simple in its design, is the most perfect heat exchanger of the double-pipe type. The article discusses the problem of determining the efficiency of a countercurrent sample cooler. The experimental apparatus for testing the cooler is described. On the basis of processing the experimental data obtained by the least-square method a semi-empirical dependence for determining the heat transfer coefficient with an error of less than 8% was obtained. The semi-empirical dependence for the cooler under consideration is applicable for temperature ranges and flow rates that occur in sample conditioning systems for thermal power plants. The results obtained make it possible not only to verify the CFD calculations aimed at improving the cooler design but also to create a high-quality mathematical model of the cooler incorporated in a mechatronic sample conditioning system, to develop an algorithm for maintaining the desired temperature and diagnosing the amount of deposits on coil surface.