Phase Change Material Engine for Micro Air Vehicle – Design and process analysis

摘要

In the past several years as the use of unmanned flying vehicles has increased dramatically, miniaturizationrnhas become a main line of developing systems. As vehicles have become smaller and smaller, the demandrnfor energy and power has made the energy source and system a limiting factor by its size and weight andrnconventional systems such as internal combustion engines [1] and battery operated electrical motors arerncutting it close to meet the specific energy and power requirements for a miniature vehicle. Lidor et al. [2]rnexamined several energy source alternatives, including springs, flywheels, thermonuclear micro devices,rnartificial muscles, carbon nano-tubes, pneumatic systems, fuel cells and phase changing materials (PCM)rnbased systems. This study focuses on the process of a proposed solution on one of the promising alternativesrn- the PCM based engine. The design is an open system, containing an insulated pressure tank holding therncryogenic fluid, a series of heat exchangers and a turbine. The design uses the heated working fluid itself tornbring heat from the environment to the cold liquid in the tank in a controlled coupled fashion in order tornsustain boiling. This paper covers analytical study of the process, evaluates its stability and offers mannersrnof controlling and regulating it. Finally, empiric results from a test bench are brought, proving the conceptrnand showing an actual PCM engine performance.