Device for Researching the Cooling Intensity of Flowing Media
Abstract
The article describes the construction of a device for researching the effect of air flow speed on the intensity of cooling of the medium that flows in the ribbed tubes of the cooler. The measure of cooling intensity is the overall heat transfer coefficient k. It is a model of a tubular heat exchanger in which horizontal and vertical movement of the individual tubes of the heat exchange surface is possible. The device will be used to obtain information about the influence of the arrangement of the heat exchange surface on the cooling performance of the exchanger. The measured values of the relevant quantities will be used as input data for the ANSYS CFX software. The software will allow to simulate the current ratios in the radiator tubes, the temperature fields along the length of the tubes and in the individual tubes of the exchanger arranged according to its height.
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Introduction
To achieve suitable transport conditions, tubular heat exchangers with a ribbed external heat exchange surface are used at compressor stations for cooling natural gas [1-4]. The transported natural gas is compressed to the required transport pressure at the compressor station, which causes an increase in its temperature. Since the increase in gas temperature causes an increase in the volume of transport gas, the quality of cooling becomes one of the transport priorities. By reducing the temperature, the mechanical stress on the gas pipeline pipes caused by the expansion of their material is also reduced, which positively affects the service life of the gas pipeline.
The device described in the article is intended to provide information on the possibility of intensifying the heat exchange when cooling natural gas during the operation of the cooler. Natural gas coolers have different cooling surfaces, which are characterized by different tube diameters, different tube wall thicknesses, different rib diameters, and different rib spacing. However, the most important thing is the way the tubes are arranged in the cooler. The pipes are placed in rows above each other in the so-called "alternate arrangement" (Fig. 1). The number of rows of tubes is different. Structurally, the individual rows create an arrangement of either crossed flow (Fig. 2) or current doubly crossed (Fig. 3).
Conclusion
The designed measuring device described in the article will make it possible to perform measurements both for crossed current and for double crossed current in various combinations of pipe arrangement (placed in rows one above the other and in alternating arrangement). The inlet (outlet) temperatures of both media will be measured just before the entrance (outlet) to the cooling space, as well as the media flow rates. Thermocouples will be used to measure the water temperature. By monitoring these temperatures, information will be obtained about the thermal performance of individual pipes, depending on their arrangement in the heat exchanger. Air temperatures will be measured just before the entrance (exit) to the cooling space and in the space between the pipes. The overall heat transfer coefficient k will be calculated from the measured values, which is a basic indicator of the intensity of heat exchange. The highest attainable overall heat transfer coefficient k will be sought through different combinations of pipe arrangement in the exchanger. The measured values will be compared with the numerical solution using FVM in the ANSYS CFX simulation tool.