Theses and Dissertations at Montana State University (MSU)
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Item The design and testing of an axial condenser fan(Montana State University - Bozeman, College of Engineering, 2021) Kirk, David Michael; Chairperson, Graduate Committee: Kevin AmendeAxial or propeller fans are a subset of turbomachinery whose application is prevalent in everyday life. In the case of heating, ventilation, air conditioning, and refrigeration (HVAC&R), fans can be a large source of inefficient energy consumption due to their physical operating nature. With the global push for more efficient systems, components of HVAC&R equipment such as fans have become a focal point for researchers in academia and industry alike. Technological improvements in research equipment such as computational fluid dynamics (CFD) and additive manufacturing play a large role in achieving these improved efficiencies. The goal of this research is to improve the efficiency of an axial fan intended for cooling a micro-channel heat exchanger that is used in rooftop condenser units. A higher efficiency retrofit fan was iteratively designed using a commercial CFD software package, Star CCM+, which constitutes much of the research conducted in this project. The iterative models show that significant efficiency gains can be achieved through incremental alterations of classical fan blade geometry elements such as pitch, camber, skew, cross section loft path, chord length, thickness, etc. A physical model of the fan design thought to be the optimal choice for experimental analysis was 3D printed and tested using an AMCA Standard 210 setup. Upon analysis of the physical test results, several discrepancies between simulated and actual results were discovered, highlighting the importance of CFD model validation in the design process. Despite the efficiency gains and advancements in user-friendly packaged software, the simulation underpredicted the power demand and incorrectly depicted the fan's performance at critical operating points showing that improper usage of these experts' tools can inadvertently lead to developed solutions with significant error. While the designed fan achieves an improved peak static efficiency and volumetric flow rate of 53.9% and 4334 CFM respectively, it ultimately did not meet the operating parameters of the specific unit it was designed for and further improvements to the CFD model are needed.Item Influence of orifice plate shape on condenser unit effectiveness(Montana State University - Bozeman, College of Engineering, 2018) Kuluris, Stephen Patrick; Chairperson, Graduate Committee: Erick JohnsonIn both residential and commercial buildings, heating, ventilation and air-conditioning (HVAC) is the largest consumer of energy. The HVAC industry works to consistently reduce their energy consumption in order to lower consumer costs and to stay competitive in the field. Therefore, improving fan efficiency of any component in an HVAC system is beneficial. A major part of the industry is to use the vapor-compression refrigeration cycle to cool buildings and an essential component of the cycle is the condenser unit. Axial fans are commonly used to move air through and cool the heated refrigerant coil. Improving axial fan performance by redesigning the casing that surrounds the fan, known as an orifice plate, is suspected to lead to a more productive condenser unit. Changing the geometry can increase performance by reducing turbulence generation both upstream and downstream of the fan, which is thought to be a major contributor to loss in fan fan efficiency. Manufacturing many different geometries in a design process to find an improved orifice plate is time-consuming and expensive. With advances in computer technologies, computational fluid dynamics (CFD) has become a low-cost alternative to iterative, physical prototyping. This work uses CFD in the design process of an orifice plate, to characterize and analyze the effects of different geometries. Fan fan efficiency and volume ow rate characterize the performance of the design, and turbulence, vorticity, and pressure visualization provides further information about the effects of design changes. The orifice geometry upstream and downstream of the fan were changed independently, and then both regions were combined into a single design. Results show that the flow upstream and downstream are affected in different ways, and contribute to overall fan efficiency through different mechanics. An improvement to the inlet region produced an fan efficiency increase of 4.8%, and the addition of an outlet region increases fan efficiency by 9.8%. The combined change in the orifice resulted in an overall increase in fan efficiency by 15.85% over the original design.