Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 84-86).The purpose of this thesis is to design and validate a controllable energy recovery device with application to photovoltaic powered reverse osmosis (PVRO). The energy consumption of a reverse osmosis plant depends significantly on the efficiency of its energy recovery process. This work presents a concept for a controllable energy recovery process, so that a system can operate optimally based on the incoming water and power characteristics. The design presented here uses a variable nozzle and a Pelton wheel to recover energy from the high pressure concentrated brine exiting the reverse osmosis membrane. The components are designed, analytically modeled using fundamental engineering principles, and experimentally tested. The experimental data is then used to check the validity of the formulated concept models. This research encompasses the modeling and testing of a variable nozzle using a needle valve to control the flow through the nozzle, and also of a Pelton bucket, to examine the effectiveness of the momentum transfer from a high velocity jet to the Pelton wheel. This research is done to examine the feasibility of this concept for potential implementation on a full scale PVRO system. The component validation is performed to prove that the concept is effective and competitive with other options.by Elizabeth Anne Reed.S.M
