José Miguel Maldonado

Bio: José Miguel Maldonado is an academic researcher from University of Lleida. The author has contributed to research in topics: Thermal energy storage & Phase-change material. The author has an hindex of 5, co-authored 10 publications receiving 96 citations.

Phase Change Material Selection for Thermal Energy Storage at High Temperature Range between 210 °C and 270 °C

Abstract: The improvement of thermal energy storage systems implemented in solar technologies increases not only their performance but also their dispatchability and competitiveness in the energy market. Latent heat thermal energy storage systems are one of those storing methods. Therefore, the need of finding the best materials for each application becomes an appealing research subject. The main goal of this paper is to find suitable and economically viable materials able to work as phase change material (PCM) within the temperature range of 210–270 °C and endure daily loading and unloading processes in a system with Fresnel collector and an organic Rankine cycle (ORC). Twenty-six materials have been tested and characterized in terms of their thermophysical conditions, thermal and cycling stability, and health hazard. Two materials out of the 26 candidates achieved the last stage of the selection process. However, one of the two finalists would require an inert working atmosphere, which would highly increase the cost for the real scale application. This leads to a unique suitable material, solar salt (40 wt % KNO3/60 wt % NaNO3).

Systematic review on the use of heat pipes in latent heat thermal energy storage tanks

Abstract: This systematic review presents and discusses the previous research about hybrid devices which combine latent thermal energy storage (TES) technology and heat pipes. A bibliometric analysis of this issue shows how hybrid systems have globally grown popularity during time, providing details about the main researchers and research centres on this particular field. Then, the identified papers are assessed and categorized in two main sections, the experimental research carried out, and the numerical modelling of hybrid systems. Experimental research is later classified regarding the operating temperature range, and their final application. Numerical studies are also further categorized, accordingly to how heat pipes were modelled in this case. This review points out the lack of experimental studies at high temperatures, especially when many simulations extended their models (validated at low temperatures) to higher temperature designs. The paper provides details about the research performed, so the gap for future investigations can be spotted.

Control strategies for defrost and evaporator fans operation in walk-in freezers.

Abstract: Heat removal is the most extended method for food preservation in food manufacturing industry by lowering food temperatures to stop microorganisms growing, which might spoil the product and could cause toxicity. Therefore, walk-in freezers are used for that purpose consuming a relevant part of the energy on service sector. The compression refrigeration system of the walk-in freezers can be blocked by the frost accumulated on the evaporator. For that reason a defrost process, which requires an important part of the energy consumption, has to be launched from time to time. In this paper, the schedule which manages the defrost process is investigated to limit its activation only when it is necessary. Moreover, different fan operation strategies were tested regarding the energy efficiency of the whole refrigeration system. This study has provided a system control strategy both for defrost and fans operation, depending on the frost built up on the evaporator. The control improves the energy performance of the whole refrigeration system.

Comparative Analysis of Energy Demand and CO2 Emissions on Different Typologies of Residential Buildings in Europe

Abstract: The building sector accounts for one third of the global energy consumption and it is expected to grow in the next decades. This evidence leads researchers, engineers and architects to develop innovative technologies based on renewable energies and to enhance the thermal performance of building envelopes. In this context, the potential applicability and further energy performance analysis of these technologies when implemented into different building typologies and climate conditions are not easily comparable. Although massive information is available in data sources, the lack of standardized methods for data gathering and the non-public availability makes the comparative analyses more difficult. These facts limit the benchmarking of different building energy demand parameters such as space heating, cooling, air conditioning, domestic hot water, lighting and electric appliances. Therefore, the first objective of this study consists in providing a review about the common typologies of residential buildings in Europe from the main data sources. This study contains specific details on their architecture, building envelope, floor space and insulation properties. The second objective consists in performing a cross-country comparison in terms of energy demand for the applications with higher energy requirements in the residential building sector (heating and domestic hot water), as well as their related CO2 emissions. The approach of this comparative analysis is based on the residential building typology developed in TABULA/EPISCOPE projects. This comparative study provides a reference scenario in terms of energy demand and CO2 emissions for residential buildings and allows to evaluate the potential implementation of new supply energy technologies in hot, temperate and cold climate regions. From this study it was also concluded that there is a necessity of a free access database which could gather and classify reliable energy data in buildings.

Experimental Methods for Engineers

Abstract: If you have an eBook, video tutorials, or other books that can help others, KnowFree is the right platform to share and exchange the eBooks freely. While you can help each other with these eBooks for educational needs, it also helps for self-practice. Better known for free eBooks in the category of information technology research, case studies, eBooks, Magazines and white papers, there is a lot more that you can explore on this site.

Heating and cooling energy trends and drivers in buildings

Abstract: The purpose of this paper is to provide a source of information on thermal energy use in buildings, its drivers, and their past, present and future trends on a global and regional basis. Energy use in buildings forms a large part of global and regional energy demand. The importance of heating and cooling in total building energy use is very diverse with this share varying between 18% and 73%. Biomass is still far the dominant fuel when a global picture is considered; the role of electricity is substantially growing, and the direct use of coal is disappearing from this sector, largely replaced by electricity and natural gas in the most developed regions. This paper identifies the different drivers of heating and cooling energy demand, and decomposes this energy demand into key drivers based on a Kaya identity approach: number of households, persons per household, floor space per capita and specific energy consumption for residential heating and cooling; and GDP, floor space per GDP, and specific energy consumption for commercial buildings. This paper also reviews the trends in the development of these drivers for the present, future – and for which data were available, for the past – in 11 world regions as well as globally. Results show that in a business-as-usual scenario, total residential heating and cooling energy use is expected to more or less stagnate, or slightly decrease, in the developed parts of the world. In contrast, commercial heating and cooling energy use will grow in each world region. Finally, the results show that per capita total final residential building energy use has been stagnating in the vast majority of world regions for the past three decades, despite the very significant increases in energy service levels in each of these regions.

Numerical investigation on thermal behaviour of 5 × 5 cell configured battery pack using phase change material and fin structure layout

Abstract: Lithium-ion battery, the indispensable part of electric vehicles or hybrid electric vehicles because of their high energy capacity and power density but usually suffer from a high temperature rise due to heat generation within a battery. This heat generation is mainly a function of the state of charge and charge/discharge rate. A passive technique like phase change material cooling has receiving a wide recognition due to its high latent heat, compact nature, and lightweight without consuming any external power. In this article, the thermal performance of the battery module containing 5 × 5 lithium-ion battery arranged in series and parallel is evaluated using phase change material. Initially, the performance of a battery module is examined with and without PCM at different discharge rate. It was found that more heat is accumulated at the interior portion of the battery pack due to mutual heating and low heat dissipation ability of PCM at a higher discharge rate. To improve such interior heat dissipation, different fin structure layout like Type I, Type II, Type III and Type IV are proposed and analysed using maximum temperature and average temperature distribution in a PCM based battery pack. It reveals that fin structure layout of Type III minimizes heat accumulation at the interior with adequate melting time among all. Furthermore, charge and discharge characteristics are investigated at different rate using rest time, convection effect and fin structure. The results indicated that use of rest time and increasing convection effect not only reduces maximum temperature but also recover melting fraction of PCM. Results also illustrate that the thermal performance of PCM based battery pack slightly get affected with the use of fin structure at lower convection, but decreases the maximum temperature by 8.17% at higher convection. Heat source a function of the state of charge and charge/discharge rate are given using Ansys-Fluent code and results are reported in the form of maximum temperature, average temperature and melting fraction.

A review on hybrid thermal management of battery packs and it's cooling performance by enhanced PCM

Abstract: Power batteries are treated as heart of the electrical vehicles and they release huge amount of heat throughout both charging and discharging processes. Hence Battery Thermal Management System (BTMS) is designed in order to control maximum temperature rise within a battery pack and to maintain even temperature distribution among the cells for increasing life span, efficiency and safety of the batteries. With an enticing characteristic feature such as low parasitic power, low weight, uniform temperature distribution among cells, passive thermal management system namely Phase Change Material (PCM) is justified as an efficient BTMS in recent years. The current work begins with the introduction of Hybrid Thermal Management System combined with PCM for enhancing cooling performance of BTMS. In addition to that, some of the thermal conductivity enrichment techniques for PCM (i.e. the usage of thermal conductive particles, cellular foams, encapsulation) are summarized. Research studies which involves various key parameters such as cell spacing, mass of PCM, thickness of PCM, specific heat capacity and thermal conductivity influencing the performance of systems are reviewed. Eventually, the results of several studies on PCM cooling are proposed in the conclusion part based on analysis of previous works.