| dc.description.abstract | Helical coil heat exchangers are types of tube and shell heat exchangers that have been implemented in processing plants, oil and gas, and refrigeration. Currently several designs have been proposed for next generation nuclear power plant designs, such as small modular reactors, high temperature reactors, and molten salt reactors. Helical coil designs are under consideration due to their compact designs and superior heat transfer efficiencies when compared to straight pipe designs. Designs are characterized by the geometry of the tube bundle, which is described as either in-line (square) or staggered (triangular). This study focuses on a helical coil design that has interlacing tube bundles, which causes the tube bundle geometry to shift between in-line and staggered. Cross sectional geometries have been previously correlated to pressure drop, friction factor, and heat transfer efficiencies depending on parameters such as pitch, tube sizing, and spacing between tubes. Additionally, tube bundles with staggered arrangements are known to cause additional disruptions in the flow which can lead to more turbulence between the tubes. Studying the effects of the tube bundle arrangement on shell side flow has typically been done by measuring pressure drops and temperature changes using pressure transducers and thermocouples respectively. This study uses the pressure sensitive paint technique to analyze pressure distributions on the surface of the tubes, and validates measurements by comparing them to static pressure transducers. Pressure sensitive paint is a technique commonly used in aerospace research studies. This technique utilizes a luminescent dye that reacts to the partial pressure of oxygen, allowing full field pressure measurements on an objects surface. Experiments using pressure sensitive paint were performed on a helical coil steam generator model at Re 4000, 6000, 8500, and 11600. Two different paint formulations were used to develop instantaneous and average pressure distributions on the surface of the tubes. This study outlines the development of a wind tunnel containing a helical coil steam generator model, and presents full field pressure measurements on the surface of tubes. Measurements show that the interlacing tube bundle geometry causes significant turbulence on tubes in the developed region of flow, but the pressure distributions are dependent upon tube location. This means adjacent tubes in the same bundle were found to not share similar pressure distribution patterns. | en |
