Design of Thermal Conductivity Measurement Device for Molten Salts at Elevated Temperatures A Project Paper [Proposal]

Design of Thermal Conductivity Measurement Device for Molten Salts at Elevated Temperatures A Project Paper [Proposal] Presented to the Queensland University of Technology School of Chemistry, Physics and Mechanical Engineering In Partial Fulfilment of the Requirements for the Degree of Bachelor of Mechanical Engineering (EN40) By Elaiza L. Luker SUPERVISORS Professor Ted Steinberg Ralf Raud 29th of April 2016 ii Abstract The use of Phase Change Materials (PCM) has been prevalent in latent heat storage applications because of its high energy storage density which plays a critical role in thermal energy storage (TES) applications (Wei Peng, Jie-min Zhou, Yuan Li, Ying Yang, & Mei-ru Guo, 2014). However, in order to determine and verify the overall effectiveness of PCMs, its thermal conductivity needs to be known, and as the exploration of eutectic mixtures for TES applications is relatively recent, it is often not documented. The relevance of this research is contextualized and supported through evidence of previous work within the project overview and literature review. This paper presents a design proposal of a thermal conductivity measurement device for use in measuring PCMs utilising the transient hot-wire method. A brief outline on the limitations and assumptions of the proposed design is also incorporated herein. Project management methods and challenges have been analysed and evaluated in order to ensure the quality and timely delivery of the project. Amongst rapid industrialization, the pursuit for cleaner energy to address challenges in sustainability is increasing more than ever; therefore, the design of this measurement device to contribute to the development of TES holds great significance in the harnessing the power of solar energy. iii Table of Contents Abstract .... ii Table of Contents ....iii 1.0 Introduction.. 4 1.1 Project Overview ..4 1.2 Literature Review.5 1.2.1 Thermal Conductivity ..5 1.2.2 Thermal Conductivity Measurement Method.6 1.2.3 Designs7 1.2.4 Sample Material .8 1.3 Thesis Statement...8 2.0 Approach/Methods 9 2.1 Design 9 2.1.1 Materials and Manufacturing....10 2.1.2 Limitations ..11 2.1.3 Assumptions11 3.0 Project Management. 12 4.0 Project Deliverables and Research Implications. 14 5.0 References... 15 Appendix 1: Design of Thermal Conductivity Measurement Device 16 Appendix 2: Project Gantt Chart.. 17 4 1.0 Introduction The thermo-physical properties of Phase Change Materials are very important in the design of efficient thermal energy storage for the continuous development of renewable energy sources. The thermal conductivity of a material, is a particularly important for TES as they play a critical role in the energy storage and recovery process. However, due to the elevated temperatures and corrosive ambience at which the system will be operating under the measurement of the sample’s thermal conductivity proves to be challenging (A. Redkin, Yu. Zaikov, O. Tkacheva, & S. Kumkov, 2015). Key challenges encountered in measuring thermal conductivity includes: (a) internal effects of convection and radiation heat; (b) limitations in materials due to operating condition; (c) Producing a design that is sustainable and economically efficient (Nunes, Lourenco, Santos, & Castro, 2003). This paper aims to address these challenges; and establish and manufacture a viable design to measure thermal conductivity of PCMs under the stated conditions. 1.1 Project Overview The growth in demand for renewable energy sources, especially solar energy, requires imperative developments in thermal energy storage (TES) capacity in order to maximize collection efficiency, as well as secure the availability and reliability of thermal energy at time intervals with little or no solar irradiation. The use of Phase Change Materials has been prevalent in latent heat storage applications due to its high energy storage density which plays a critical role in thermal energy storage applications (Wei Peng, Jie-min Zhou, Yuan Li, Ying Yang, & Mei-ru Guo, 2014). In collecting solar energy for storage, technologies and processes for Concentrating Solar Thermal Power (CSTP) is used. CSTP is a process that utilizes mirrors in concentrating solar thermal energy onto a small area within a heat exchanger in order to attain very high temperatures which is absorbed by a heat transfer fluid or PCMs in an intermediate cycle (Pitz-Paal, 2008). PCMs are advantageous as TES due to its capacity to store and emit large quantities of energy during solid to liquid transformations as latent heat (LH), whilst only requiring small volumes of the heat transfer fluid. For LH storage and discharge, smaller temperature fluctuations are required to attain high storage density relative to sensible heat (SH) storage, which stores as a liquid or solid form rather than storage during a substance’s phase change (Pielichowska & Pielichowski, 2014).