Pedro D. Silva

Transient behaviour of a latent-heat thermal-energy store: numerical and experimental studies

The phase change material (PCM) considered is a commercial paraffin wax. The main enclosure that contains the wax has a rectangular geometry and is placed in a vertical position. One of the walls is heated at constant rate during the charge process and the other wall is cooled by an airflow stream during the discharge. To describe the performance of the store a one-dimensional model based on the enthalpy method is developed. An apparent specific heat of the PCM is determined using a differential scanning calorimeter (DSC). This parameter permits the enthalpy of the PCM to be determined, and linearized for the numerical model. The results show that the simplified numerical model can be used to predict, with reasonable accuracy the dynamic performance of this kind of heat exchange unit.

Handbook of research on advances and applications in refrigeration systems and technologies

In recent years, the sustainability and safety of perishable foods has become a major consumer concern, and refrigeration systems play an important role in the processing, distribution, and storage of such foods. To improve the efficiency of food preservation technologies, it is necessary to explore new technological and scientific advances both in materials and processes. The Handbook of Research on Advances and Applications in Refrigeration Systems and Technologies gathers state-of-the-art research related to thermal performance and energy-efficiency. Covering a diverse array of subjects-from the challenges of surface-area frost-formation on evaporators to the carbon footprint of refrigerant chemicals-this publication provides a broad insight into the optimization of cold-supply chains and serves as an essential reference text for undergraduate students, practicing engineers, researchers, educators, and policymakers.

Characterization of the Specific Electrical Energy Consumption of Agrifood Industries in the Central Region of Portugal

This paper provides a characterization of the electrical energy consumption of agrifood industries located in the central region of Portugal that use refrigeration systems to ensure the food safety. The study is based on the result analysis of survey data and energy characteristics of the participating companies. The agrifood industries included in the survey belong to the following sector: meat, dairy, horticultural, distribution and wine. The comparison of energy indicators for the specific electrical energy consumption of companies of a sector and between sectors is analysed and discussed, providing reference levels for the energy performance of agrifood industries. Since the agrifood sector accounts for high level of energy consumption, the energy performance level knowledge can promote the rational use of energy as well as helping on the decision making of practice measures for the improvement of the energy efficiency.

Characterization Of The Specific Energy Consumption Of Electricity In The Portuguese Sausage Industry

The sausage is an ancient food type that is nowadays considered as a delicatessen. Sausages are categorized within the deli sector as meat sub products. It is a food product preferred by consumers due to its nutritional value and organoleptic characteristics (wide range of flavours and textures). There are many types of sausages, with around 1200 different varieties (according to German classification), classified into types according to different criteria such as types of ingredients, consistency, and preparation (raw, cooked, pre-cooked, dry). In the UK, 196,152 metric tons of sausages were consumed during 2011, valued in

Specific Electrical Energy Consumption and CO2 Emissions Assessment of Agrifood Industries in the Central Region of Portugal

1.2 billion, while in the US this value was around

Computational Tool for the Energy Performance Assessment of Horticultural Industries Case Study of Industries in the Centre Inner Region of Portugal

20.4 billion two years before. The heating and cooling processes during sausage production are indispensable technologies to ensure both the specific organoleptic characteristics and properties conservation through time. This paper characterizes the production process and the energy consumption of sausages processing industry in Portugal (20 industries) and discusses the average specific energy consumption (SEC) of electricity and its standard deviation. The average value of this indicator for the sample was 660 kWhe/ton raw material. The energy consumption of this type of industry is mainly that of electricity (82%). Several electricity savings, estimated at 23.9%, can be achieved by implementing simple practice measures in the refrigeration systems.

Control, Regulation and Command System of Hydronic Radiant Floors Heating by Wireless and Energy Harvesting Sensors and Actuators

This paper provides a characterization of the electrical energy consumption of agrifood industries located in the central region of Portugal that use refrigeration systems to ensure the food safety. The study is based on the result analysis of survey data and energy characteristics of the participating companies belonging to the following agrifood sectors: meat, dairy, horticultural, distribution and wine. Through the quantification of energy consumption of companies is possible to determine the amount of greenhouse gases (GHGs) emissions indexed to its manufacturing process. Comparing the energy and GHGs emissions indexes of companies of a sector and between sectors is possible to create reference levels. With the results of this work is possible to rating the companies in relation to reference levels of energy and GHGs emissions and thus promote the rational use of energy by the application of practice measures for the improvement of the energy efficiency and the reduction of GHGs emissions.

Introduction to Sustainable Food Production

Food processing and conservation represent decisive factors for the sustainability of the planet given the significant growth of the world population in the last decades. Therefore, the cooling of any food products has been subject of study and improvement in order to ensure the food supply with good quality and safety. A computational tool for the assessment of the energy performance of agrifood industries that use refrigeration systems was developed. It aims to promote the improvement of the energy efficiency of this industrial sector. The computational tool for analysis of the energy profile is based on a set of characteristic parameters used for the development of correlations, including the amount of raw material, annual energy consumption and volume of cold stores. In this paper, the developed computational tool was applied to companies in the horticultural sector, specifically to resale-type companies. The results obtained help on the decision making of practice measures for the improvement of the energy efficiency.

THERMAL PERFORMANCE, USAGE BEHAVIOUR AND FOOD WASTE OF DOMESTIC REFRIGERATORS IN A UNIVERSITY STUDENT COMMUNITY: FINDINGS TOWARDS CITIES SUSTAINABILITY

This paper presents the development of an innovative control, regulation and command system for hydronic radiant floors, more flexible and efficient that guarantees a better thermal comfort to the user and simultaneously improves the energy efficiency of this type of heating system. The majority of the actual control of hydronic radiant floors is done by thermostats that measure the air temperature and control the actuators (pumps and valves) in order to maintain the room at the specified temperature. These systems requires the frequent adjustment of thermostats set-point in order to obtain thermal comfort as it depends on other factors than just the air temperature, such as, the air humidity, external environmental conditions, radiant temperature, among others. This paper presents a control, regulation and command solution that requires minimum user intervention, as the user only has to choose the desirable thermal comfort level. The control algorithm is based on the calculation of PMV (Predicted Mean Vote) index as defined on Thermal Comfort Standard ISO 7730. Another advantage of the proposed system is related to the wireless and energy harvesting sensors and actuators that provide much more flexibility to the system.

Numerical modeling of cold room’s hinged door opening and closing processes

Abstract This chapter presents an overview of the current production methods for food and food ingredients, and describes the options for making healthier foods in a more sustainable manner. The current manner of producing food products has a large impact on the environment. Three main causes are responsible for inefficiencies in food production. Those are the increased use of products from animal origin, the inefficient use of food products once produced, resulting in waste generation, and the current setup of food processes and processing chains. This chapter summarizes the recent developments and sketches future scenarios for novel designs of food processes and process chains aimed at reduced environmental impact.