Development of a pellet boiler with Stirling engine for m-CHP domestic application

Abstract

A new sustainable technology has been designed by Fondazione Bruno Kessler through its unit Renewable Energies and Environmental Technologies. This technology is realized integrating in a single system (1) a Stirling engine (mRT-1K) from a pre-engineering design of Allan J. Organ; (2) a micro-heat exchanger technology, to reduce the net transfer unit deficit on the hot side of the heat engine; (3) a customized pellet boiler, able to extract electrical and thermal power; and (4) a customized hydraulic circuit, connecting the cool side of the Stirling engine and the heat generation on the second section of the pellet boiler. The objective of this paper was to present a new technology for the micro-cogeneration of energy at a distributed level able to be integrated in domestic dwellings. Most part of the available biomass is used in buildings for the generation of thermal power for indoor heating and, in minor cases, for hot sanitary water. In the Province of Trento, 88% of the biomass is used for this purpose. The full system is actually under integration for the test phase and not yet tested. The first tests on the single components have confirmed preliminary results on the Stirling engine with respect to the tolerances, pressurization, and proper integration of the electrical generator-driven control system. The pellet boiler has been tested separately, confirming an overall thermal efficiency of 90%.

Modern Small and Microcogeneration Systems—A Review

“…Stirling engine heads adapted to receive heat from solid fuel systems are intensively developed by means of advanced numerical analyses. The example of the concept Stirling engine with an additional heat exchanger located at an angle of 45 • , designed specifically for the system analyzed by the authors [79,80] is shown in Figure 11. The manufactured engine based on this design is shown in Figure 12.…”

“…Figure13. Side view of a heat exchanger adapted to operate with a Stirling engine and a solid fuel system[80].…”

4.6 Stirling Engines

“…Among these contributions we find the system infinea [52] or solar dish [53]. Other precommercial prototypes (see Relevant Websites section) have been developed in the field of cogeneration of electricity and heat (CHP), the cogeneration units Cleanenergy [51], Whispergen [54], Stirling DK, and the "Sunmachine" gas or biomass [55]. All solutions are based on high-temperature sources.…”

Energetic and Exergetic Analysis of a Heat Exchanger Integrated in a Solid Biomass-Fuelled Micro-CHP System with an Ericsson Engine

“…Figure 1). The literature mentions several solid biomass-fuelled micro-CHP systems associated to various cogeneration devices: a Stirling hot air engine [1][2][3][4], an Organic Rankine Cycle (ORC) turbine [5] and a thermoelectric generator [6]. Although no study has dealt with the performances of a solid biomass-fuelled micro-CHP system with an Ericsson hot air engine yet, this cogeneration device is well adapted in such facilities [7].…”

“…To determine the working conditions and the performances of the solid biomass-fuelled micro-CHP systems and of their components, an energetic analysis is mostly applied [1,2,5,6]. Such studies may be completed with exergetic analyses, following the example presented by [14] with a natural gas micro-CHP system, in order to highlight the zones of exergy destruction and allow an improved optimization of the working conditions to enhance the performances.…”