Experimental study of a photovoltaic solar dryer

This experimental work focuses specifically on the development and construction of a prototype and the study of different strategies to optimize food drying from solar energy. The main study variable is the efficiency of the solar dryer. In order to optimize the system and increase the drying rate it was decided to use a photovoltaic panel which will power a resistive load - thus obtaining higher air temperature which enters the drying chamber. First, are shown some considerations about the range of applications and methods of harnessing solar energy, emphasizing how important it is to conserve food products through solar drying. To elucidate this concept existing models of solar dryers are reviewed, highlighting the most efficient and representative of each category, in order to understand the work already developed in this area. All experimental results were obtained in drying trials during the summer of 2016. These results demonstrate the advantages and disadvantages of each strategy adopted. Calculations were made and performance parameters discussed, allowing to take conclusions about the modus operandi and design of this type of units. In order to benefit the most of the energy generated, and thus reduce waste, certain measures have been identified that promote the correct use of PV panels for drying agricultural products. All of this work is for the purpose of being adopted by local farmers.info:eu-repo/semantics/publishedVersio

The cherry drying as a complementary conservation process to conservation in cold

Cherry is greatly enjoyed by consumers because of its excellent organoleptic and nutritional characteristics. This fruit is of the non-climacteric type, which forces its immediate commercialization after harvesting or else it should be properly conserved in cold. Every year there is a big waste of fresh cherry because he could not be marketed before deteriorating both in cooling chambers, or even in their own cherry trees due to a rapid ripening. In this project, the process of making cherry raisins is studied so as to provide increased use of fresh cherry. For that purpose, three different processes of dehydration of fresh cherry have been used, such as freeze drying, hot-air drying and solar drying. Three types of samples of pitted cherries were also used - natural cherry, blanching cherry and bleaching cherry with osmotic solution of fructose. In order to assess the performance of the dryers the curves of drying rate were determined and to assess the quality of the cherry raisins, fundamental parameters were determined, namely moisture content, water activity (aw), texture, total soluble solids and total acidity. The results show that the drying rate of cherry samples is similar in the lyophilizer and hot air dryer, and yet faster in the latter. The dryer with lower rate drying and hence with higher drying time was the solar dryer. The characteristics of the cherry raisins depend on the type of dryer used and the pre-treatment used. The blanching pretreatment proved to be the most suitable. Regarding dryers, the solar dryer provided good quality cherry raisins, showing great potential at industrial level with the advantage of not consuming energy.info:eu-repo/semantics/publishedVersio

Specific electrical energy consumption and CO2 emissions assessment 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 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.info:eu-repo/semantics/publishedVersio

The 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 $1.2 billion, while in the US this value was around$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.info:eu-repo/semantics/publishedVersio

Potential of energy savings in Portuguese meat industry

In Portugal the meat sector occupies the highest rank within the food industry having its electricity consumption grown at a high pace mainly due to the intense use of refrigeration systems. This paper assesses the electric energy consumption profile of Portuguese meat industries and estimates the potential savings with a set of simple energy efficiency measures which result from the best practices in the sector. Taking in account the fieldwork, some of the most relevant measures carried out are: to improve production process management in order to avoid the use of cold chambers partially loaded; to improve thermal resistance of the buildings envelope, cold chambers and refrigeration pipes; to avoid installation of condensation groups in warm places (exposed to solar radiation or in non-ventilated attics). The results show a potential reduction in electricity consumption of 24% for slaughterhouses (474 MWh), 13% for sausage houses (322 MWh), and 8% for ham production (708 MWh).info:eu-repo/semantics/publishedVersio

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.info:eu-repo/semantics/publishedVersio

Development of an experimental unit for studying the solar drying process

The removal of moisture by drying, prevents the growth and reproduction of these microorganisms, which cause rotting, and minimizes many of the reactions of deterioration from moisture, revealing itself a crucial preservation method. Portugal is a country with great potential for exploitation of solar energy, the implementation of a drying system based on this renewable source, facing devices with high energy consumption and hence more expensive, is attractive. With this, the present work emerges, in order to, by building a sustainable drying model, evaluate their performance, so that can be a good solution. First, were done characterization tests with the dryer unload, studying the temperatures and the relative humidity (RH) inside the drying chamber. The influence of various air gap heights and of operation modes, under natural and forced convection were studied. The developed unit was subsequently used in cherry drying. The first drying test, allowed dry 15 kg cherry in 124 hours. The second with 25 kg was carried out under adverse conditions, therefore presented an additional drying time of 25 hours from the first. The results of the studies realized indicate great potential of the drying mechanism proposed, capable of reaching temperatures of 55 °C inside the drying chamber, for an ambient temperature and humidity of 31,7 ºC and 28%, respectively, and an intensity of solar radiation of 918 W/m2.info:eu-repo/semantics/publishedVersio

Characterization of refrigeration systems in the Portuguese food processing industry

This study is within the activities of Project “PrunusPÓS - Optimization of processes for the storage, cold conservation, active and/or intelligent packaging and food quality traceability in post-harvested fruit products”, project n.º PDR2020-101-031695, Partnership n.º 87, initiative n.º 175, promoted by PDR 2020 and co-funded by FEADER within Portugal 2020.This paper presents the results of audits performed in 60 companies of the food processing industry, specifically of meat, dairy, horticultural and bread products. The refrigeration volume, type of refrigeration system, refrigerant, building and insulation materials of infrastructure and refrigeration chambers, average air temperature and humidity, and the energy consumption are presented, compared and discussed per sector. The analysis allows to provide several measures and best practices aimed for the improvement of the thermal performance and energy efficiency of the food processing industry. The implementation of simple and very cost-effective transversal electricity savings measures such as awareness and/or training of operators, proper maintenance and monitoring tasks can benefit the sector. Tailored energy efficiency measures by sector, which may offer savings on several levels, are discussed. These best practices may increase productivity and competitiveness and reduce the environmental impact, and thus improve the global sustainability of the Portuguese food sector.info:eu-repo/semantics/publishedVersio

Computational tool for the analysis and simulation of cold room performance in perishable products industry

Perishable products such as meat, fruit and dairy products are some of the major food products preferred by consumers due to their nutritional and organoleptic characteristics. The conservation of their properties through time is usually ensured by storing them in rooms with controlled air temperature and humidity. The refrigeration systems that accomplish these environmental conditions are the main responsible by the electrical energy consumption in food sector industries. With the aim to promote an improvement of its energy performance, a computational tool for the analysis and simulation of cold rooms performance was developed. It allows the analysis of the behaviour of relevant parameters, such as: raw material quantity, cold rooms volume, refrigeration systems power, among others. The preliminary results of the practical application of this tool show its usefulness on the decision making for energy efficiency measures to reduce the specific energy consumption in perishable products industry.info:eu-repo/semantics/publishedVersio

Energy consumption and energy efficiency measures in the Portuguese food processing industry

In the present study, simple energy surveys and audits were performed in 60 companies of the processing industry of meat, dairy, horticultural and bread and pastry products. 20 of the companies analyzed were located in the North region, 21 in the center region and 19 in the Alentejo region. The number of refrigeration chambers, the building infrastructure and the energy consumptions of the equipment used in the manufacturing processes were evaluated. This study allows to compare the energy consumption of the different manufacturing processes of regional food products. The aim of the study is to present several measures and best practices aimed for the improvement of the energy efficiency of the food sector as all. The implementation of simple and very cost-effective transversal electricity savings measures such as awareness and/or training of operators, proper maintenance and monitoring tasks, can benefit the sector. The tailored energy efficiency measures by sector are discussed. These energy efficient practice measures can offer savings on several levels, which may increase productivity and competitiveness and improve the environmental impact, and thus the global sustainability of the Portuguese food sector.info:eu-repo/semantics/publishedVersio