engleski

Analysis of HVAC Duct System Pressure Losses on a Cruise Ship

The main goal of this Thesis was to evaluate different approaches to pressure loss calculation for HVAC ducts systems on a cruise ship while considering calculation constraints arising during design process, and its effect on selection of fans. In the Thesis, history, utilization of HVAC design on ships, and its difference to land-based systems were presented. Also, pressure and airflow relations regarding later pressure loss analysis were discussed, followed by a brief explanation of fan-system interaction and System Effect. Methodology in evaluation of calculation approaches consisted of comparison of pressure loss results calculated by two different software: Excel Calculation Tool and Trimble Nova®. Firstly, systems were calculated using Trimble Nova® with appropriate dynamic loss coefficients utilized by the software. The critical duct path was then introduced into Excel Calculation Tool, where pressure loss was calculated for the system elements with corresponding dynamic loss coefficients. These results were the multiplied by a safety factor and compared both to commissioning total pressure rise measured over fan and pressure rise anticipated in a predesign phase of a project. The systems were divided into 4 groups, depending on their design and purpose. These groups were: AHUs, Fans with FC, Fans without FC, and FCUs. The pressure loss results that had higher value than the commissioning data are regarded as positive, while the result that showed lower value compared to commissioning were considered negative. For all groups where real pressure loss can be determined due to the regulation of the FC or EC motor, a comparison of the assumed and measured values showed large differences. Additionally, comments were given for possible improvements, which would include pressure loss comparison table, investigation of software, improved communication between engineer groups, changes to calculation tools, and the possibility of utilizing acoustic calculation. Finally, financial analysis has been done. A conclusion has been made that, in the case of AHU fans, due to the constraints of already installed units and a wide range of working of the fans, downsizing didn’t take place. However, if smaller pressure losses are assumed and stated to the manufacturer before delivery of the unit, possible changes and savings could be possible. For Fans with FC, downsizing of both motors and fans is possible, resulting in initial cost savings for the company, and operational costs for ship-owner.

cruise ship, HVAC, pressure loss calculation

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