EXPERIMENTAL FEATURES OF A DIRECT HELICAL-COIL EVAPORATOR FOR AN MICRO-COGENERATION ORGANIC RANKINE CYCLE BASED SYSTEM

The objective of the work partially described in this paper is to fill-in the technological-gap that is preventing the micro-CHP ORC based systems of performing direct vaporization of the organic fluid. This was ensured through the construction and characterization of an evaporator able to perform and safely support the direct vaporization. The approach differs from the systems that are being developed at universities and research centers working in the field, which are using an indirect process (usually with water or thermal oil warmed up in a standard or condensing boiler) to vaporize the working fluid. Important benefits like reducing of thermal inertia and consequentially a minor transient phase in the start-up, reduced system dimensions as well as increasing of the global efficiency are expected. This benefits can be crucial for comparison between micro-CHP systems with actual combi-boilers already implemented in individual households or public buildings. All the development phases were performed taking into consideration the specific requirements of the retrofitable micro-CHP appliance being developed within the company SCIVEN. This paper describes details of the features of the first prototype where not all of those design requirements were taken into account once the focous was centered in the working principle definition.