Master of Science / Department of Mechanical Engineering / Donald Fenton / The need to store and access electronic information is growing on a daily basis as more and more people conduct business and personal affairs through email and the internet. To meet these demands, high energy density data centers have sprung up across the United States and around world. To ensure that vital data centers run constantly, proper cooling must be maintained to prevent overheating and possible server damage from occurring. Emergency cooling systems for such systems typically utilize traditional batteries, backup generator, or a combination thereof. The electrical backup provides enough power to support cooling for essential components within the data centers. While this method has shown to be reliable and effective, there are several other methods that provide reliable emergency cooling at a fraction of the cost. This paper address the lack of information regarding the initial, operation, and maintenance costs of using Thermal Energy Storage (TES) tanks for emergency cooling. From research and various field examples, five emergency cooling system layouts were designed for various peak cooling loads. Looking at the different cooling loads, components, and system operations an economic evaluation of the system over a 20 year period was conducted. The economic analysis included the initial and maintenance costs of each system. In an effort to better understand power consumption of such systems and to help designer’s better estimate the long term costs of TES tanks systems, five layouts were simulated through a program called TRNSYS developed for thermal systems. To compare against current systems in place, a benefit to cost ratio was done to analyze TES versus a comparable UPS. The five simulated systems were one parallel pressurized tank, one parallel and one series atmospheric tank, one parallel low temperature chilled water, and one series ice storage tank. From the analysis, the ice storage and pressurized systems were the most cost effective for 1 MW peak cooling loads. For 5 MW peak cooling loads the ice storage and chilled water systems were the most cost effective. For 15 MW peak loads the chilled water atmospheric TES tanks were the most cost effective. From the simulations we concluded that the pressurized and atmospheric systems consumed the least amount of power over a 24 hour period during a discharge and recharge cycle of the TES tank. From the TRNSYS simulations, the ice storage system consumed 22 – 25% more energy than a comparable chilled water system, while the low temperature storage system consumed 6 – 8% more energy than the chilled water system. From the benefit-cost-ratio analysis, it was observed that all systems were more cost effective than a traditional battery UPS system of comparable size. For the smaller systems at 1 MW the benefit-cost-ratio ranged between 0.25 to 0.55, while for larger systems (15 MW) the ratio was between 1.0 to 3.5 making TES tanks a feasible option for providing emergency cooling for large and small systems.

Master of Science / Department of Mechanical and Nuclear Engineering / Donald L. Fenton / Emergency cooling systems are applied to any application where the loss of cooling results in damage to the product, loss of data, or equipment failure. Facilities using chilled water for cooling that experience an electrical power outage, even a small one, would cause the chiller to shut down for 20 minutes or more. If emergency cooling is not available, temperatures would continue to increase to dangerous levels, potentially damaging the facility. Examples of facilities that could be protected by having emergency cooling systems are data centers, hospitals, banks, control rooms, laboratories, clean rooms, and emergency shelters among others. This project addresses the current lack of information and methods needed to correctly design emergency cooling systems. Three application uses were investigated for the possible benefits of having emergency cooling systems. The software TRNSYS was used to simulate five typical emergency cooling systems for each of the three applications. The characteristics and differences of the systems developed from the simulations were then analyzed and documented. The five systems simulated include a pressurized chilled water tank (parallel), atmospheric chilled water tank (parallel and series), low temperature chilled water tank (parallel), and ice storage tank (series). Simulations showed that low temperature chilled water tanks were less stratified than regular chilled water tanks by approximately 10%. Simulations also showed that the differences between atmospheric and pressurized tanks were negligible. Each tank discharged energy in the same manner and managed to replenish itself in the same amount of time. Examination of the different system configurations showed that tanks in series with the thermal load have issues with recharging due to its inability to isolate itself from the thermal load. It was also observed that while low temperature chilled water and ice storage tanks had the potential of reducing the storage tank volume, the amount of time ragged cooling will last is decreased by at least a factor of two. The examination of the five systems produced the desired design methodologies needed to address the lack of information on emergency cooling systems. With the reported information designers can effectively engineer systems to meet their needs.

My thesis deals with the design of an experimental emergency cooling device of the reactor pressure vessel (RPV). It consists of two parts, the theoretical one and practical one. Different molten corium cooling methods in terms of their efficiency and comparison are introduced in the theoretical part. The design of an experimental emergency cooling device, which incorporates a model channel past the reactor pressure vessel , is presented in the practical part. The cooling device consists of a model channel past the reactor pressure vessel, condensator, which takes away the heat generated by the reactor pressure vessel and the pump of a secondary loop. Next, thermal and hydraulic calculations are given in this section. The conclusion is devoted to the evaluation of particular cooling technologies and their comparison in terms of nuclear and technical safety.