Eurotherm Seminar

p. 1-10

Presentation's date: 2014-05-28

Abstract:

Low Thrust Cryogenic Propulsion (LTCP) systems [1] need a thermal energy storage acting as a heat accumulator, where a cryogenic flow of (LOx) propellant is gasified inside, under a fast transient evaporation process. The heat accumulator is heated by means of a secondary fluid (typically He or N2) which is exchanged from fuel cells. The heat exchanged or stored between both fluid flows is assured by means of a thermal energy storage tank filled of a Phase Change Material (PCM). A numerical model of the thermal and fluid-dynamic behavior of the two-phase flow inside ducts working under cryogenic conditions, coupled with the analysis of the PCM accumulator is proposed [2]. The numerical analysis is based on: i) a one-dimensional and transient integration of the governing equations (conservation of mass, momentum and energy) for the fluid flow of propellant, and ii) a multi-dimensional and transient integration of the conservative governing equations in the region occupied by the PCM, taking into account turbulence modeling for solving the convection phenomena involved. The solid elements are modeled considering a multidimensional and transient treatment of the thermal conduction equation. The numerical results are experimentally validated by means of a series of experimental tests [3] [4]. The comparative analysis shows the good agreement between both numerical results and experimental data. Different results under working conditions of the cryogenic flow and/or the PCM material, shows the possibility of this model for design optimization purposes.]]>

REHVA World Congress

Presentation's date: 2013-06

Abstract:

The sensible heat accumulation is an efficient and low-cost way of storing thermal energy for its direct or indirect reutilization in typical building processes as space heating and sanitary hot water generation. The authors are developing both numerical and experimental tools for the study and optimisation of this kind of systems, focusing on the analysis of a specific sensible heat accumulator based on a cylindrical tank with an internal coiled pipe. The numerical simulation has been performed using a high-level platform that links two codes to solve the system. The fluid inside the tank is solved with a CFD&HT (Computational Fluid Dynamics & Heat Transfer) software called TermoFluids and the fluid flow inside the pipe is solved considering a quasi-homogenous fully-implicit one-dimensional model, where the governing equations are discretized along the whole tube domain. The resolution of the pipe wall in a detailed way couples both fluid solvers. On the other hand, an experimental infrastructure has been developed for the analysis of the system, which has been instrumented to provide detailed information of its heat storage capacity and temperature map. Several temperature sensors are incorporated in the heat accumulator at different heights and radius inside the tank. For the internal flow, the mass flow rate is measured, as well as the inlet and outlet temperatures. Different internal flow rates and operational temperatures have been studied both numerically and experimentally. From the results obtained it can be said that the device shows interesting heat storage capacities, while the numerical platform shows promising comparison results against the experiments.]]>

IIR International Congress of Refrigeration

p. 1-8

Presentation's date: 2011-08-21

Abstract:

The aim of this work is to perform a high-level numerical simulation platform for heat storage systems with or without phase change materials (PCM). The simulation allows to predict the thermal behavior of the aforementioned systems and to carry out parametric studies in order to find the most appropriate geometry and materials for different operating conditions. The studied storage system here presented is composed by a cylindrical tank and a pipe tube inside the tank. The proposed methodology is based on the numerical simulation of the storage system by means of Computational Fluid Dynamics & Heat Transfer (CFD&HT) software, called TermoFluids, which is used in this work for solving the heat transfer in the fluid flow inside tank. In the case of fluid flow inside pipe, it is solved considering a quasi-homogenous fully-implicit one-dimensional (1D) model, where the governing equations are discretized along the whole tube domain.]]>

Abstract:

Considering the current state-of-the-art in Thermal Energy Storage technologies, the main motivations of this project are: To reduce the high costs in existing storage systems, To look for viable possibilities for thermal energy storage systems which are still undeveloped The aim is the development of cost-effective thermal storage systems for Concentrated Solar Power, with an investment cost of less than 25€/kWh of storage capacity. One of the outcomes of this project will be to provide the Consortium with experimental and numerical tools/platforms for future designs and industrial technological support, attracting customers of the solar energy field.]]>