Abstract
Heat-loading on working fluids such as those used on Hydraulic and Braking systems have been considered to cause a negative effect due to performance inefficiencies and pressure drops brought on by designed features such as pressure regulators and relief valves. For this type of working systems the negative effect causes toward the working fluid are in the form of heat, which if not properly regulated can cause a degradation to the performance (reduction of working force) of the hydraulic system, as well as the breakdown of the hydraulic fluid, and an increase in the wear to critical components such as seals, bearings (as used in pumps and valves that could lead to premature failure of the hydraulic system. Normally, this heating effect is addressed by the integration of devices such as a heat exchanger or properly sized fluid reservoirs into the hydraulic system. By doing so this effectively dissipates or reduces the amount of thermal energy residing in the heated fluid. Such preventive methods help maintain a sufficient operating temperature range within the system, protecting components. However, what if this negative heating effect that occurs within hydraulics systems could be harnessed, even promoted to produce a positive product in the form of raising the temperature in water such as could used to design an instantaneous hot water heater system? The work laid out in this thesis is intended to evaluate if the use of heat loading in the form of pressure drop and pump inefficiency can be used as a means to intentionally increase the temperature of an incompressible fluid (water, H2O), through mathematical and computation studies. Two mathematical equation models were performed providing initial predictions that a pressure drop of 5000psi will produce about 14-degF of heating to the fluid. Taking these predictions, 3D simulation models were created and were used to validate the mathematical predictions to show that pressure drop of different pressure levels does convert the potential energy in the fluid (in the form of the raised pressure) and converts it to thermal energy (in the form of increase fluid temperatures). The simulation portion on this thesis will show the setup and process for creating each simulation. The process is first started with having models of both pressure relief valves and of an orifice to be created to simulate both direct and hybrid heating of flowing water. Each model is then meshed in to the computational fluid dynamics (CFD) preprocessor, ANSYS FLUENT. After the CFD software setup was configured, each individual model is simulated in FLUENT and the results are compared to determine the most optimized and efficient model for heating water to a specified temperature level. By using two different relief valve designs, it was determined that the pressure drop is the primary contributor to the temperature. By comparing the three types of relief devices, the orifice was determined to provide the most simplest and cost effective design, but also requires that the water flowing through the restriction must be accurately conditioned so that a specific flow rate and inlet pressure is maintained or the output temperature would be negatively affected (lower than predicted temperature). Finally 3D model of inlet tank concepts were analyzed in ANSYS FLUENT to determine that a 7-8-degF increase to inlet water could be provided which could reduce the amount of components required to heat the water to an approximate range of 120-140-degF. Finally, this thesis will provide direction to what further activities would be required to validate both the mathematical and simulated results and provide conceptual design ideas.