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This article provides a theoretical energy performance and carbon footprint analysis of the hydrofluoroolefin HFO-1234ze(E) and the mixture R-515B as low global warming potential (GWP) refrigerants to replace the hydrofluorocarbon HFC-134a in different heat pump applications. The reference configuration is a single-stage cycle with an internal heat exchanger (IHX). In this way, the impact of the IHX on medium and moderately high temperature heating applications has been investigated. HFO-1234ze(E) and R-515B result in approx. 25% lower heating capacity than HFC-134a due to a diminution of the latent heat of vaporisation and suction density. The heating capacity difference between HFO-1234ze(E) and R-515B remains below 2%. The heating coefficient of performance (COP) of the alternative low GWP refrigerants is comparable to that of the HFC-134a at the proposed conditions. The environmental analysis illustrates that HFO-1234ze(E) and R-515B can reduce down to 18% and 15%, respectively, the equivalent CO2 emissions compared to HFC-134a in low-temperature space heating applications. In addition, this reduction arrive at 78% when compared to a natural gas boiler, considered as the conventional heating technology in moderately high temperature applications (domestic hot water, industrial processes, and radiators). Although HFO-1234ze(E) and R-515B present comparable energy and environmental performance, the latter refrigerant has an advantage in regard to installation safety requirements as a non-flammable refrigerant (A1).

Higher Education Institutions must consider the most recently developed technologies to increase energy efficiency. A significant share of the heat used in industry is wasted while still being at usable temperature levels and hence a significant energy saving potential is present in this sector. The Organic Rankine Cycle (ORC) is a system that uses low-grade waste or renewable heat to produce electricity and lower grade heat and can be integrated into a variety of applications. In this paper, an introduction to ORCs is presented, and then, a practical example of a laboratory session using an experimental test bench based in this technology in a last year bachelor’s degree course is detailed. A commercial ORC machine was run in the laboratory session, where the students were able to explore its operation through the graphical interface. They applied the main thermodynamic concepts in the interpretation of the behavior and seen the utility of this science in recently developed environmentally friendly technologies. Then, the students simulated a real case based on the valorisation of exhaust gases from an engine installed in a wastewater treatment plant. Students agreed that the combination of both parts in this session is beneficial for their understanding and that ORC machines are a viable solution to control climate change. Las instituciones de educación superior deben considerar las tecnologías desarrolladas más recientemente para aumentar la eficiencia energética. Una parte importante del calor utilizado en la industria se desperdicia mientras se mantiene en niveles de temperatura utilizables y, por lo tanto, existe un potencial significativo de ahorro de energía en este sector. El Ciclo de Rankine Orgánico (ORC) es un sistema que utiliza residuos de bajo grado o calor renovable para producir electricidad y calor de menor grado y se puede integrar en una variedad de aplicaciones. En este documento, se presenta una introducción a los ORC y, a continuación, se detalla un ejemplo práctico de una sesión de laboratorio con un banco de pruebas experimental basado en esta tecnología en un curso de licenciatura del año pasado. Se ejecutó una máquina de ORC comercial en la sesión de laboratorio, donde los estudiantes pudieron explorar su funcionamiento a través de la interfaz gráfica. Aplicaron los conceptos termodinámicos principales en la interpretación del comportamiento y vieron la utilidad de esta ciencia en tecnologías recientemente desarrolladas amigables con el medio ambiente. Luego, los estudiantes simularon un caso real basado en la valorización de los gases de escape de un motor instalado en una planta de tratamiento de aguas residuales. Los estudiantes acordaron que la combinación de ambas partes en esta sesión es beneficiosa para su comprensión y que las máquinas ORC son una solución viable para controlar el cambio climático.

Several environmental protection policies have been enforced restricting working fluids with high global warming potential (GWP) values used in many types of refrigeration and heat pump systems. However, ultralow-temperature (ULT) refrigeration has not been included, which commonly uses refrigerants with very high GWP values (such as R23 and R508B). Therefore, publicly available research programs seeking low GWP alternative refrigerants do not cover this application and the transition to more environmentally friendly fluids is slowed down. This work presents a comprehensive review that summarizes and discusses the available studies about ULT refrigeration systems. The current status of the technology, system architectures and refrigerants are analyzed. Moreover, the transition towards low GWP refrigerants is proposed, presenting the most promising low GWP alternatives. The most commonly used architectures for ULT refrigeration are the two-stage cascade and auto-cascade, in which the use of ejector has recently been considered in research papers. R170 and R1150 are the available natural refrigerants suitable for ULT, but they have not yet been included in many flammability and risk assessment studies. The A2 hydrofluoroolefin R1132a has been recently proposed as a blend component to avoid problems of stability. However, more information is still necessary to start with simulation and experimental studies. R41 could be an alternative due to its low GWP and suitable normal boiling point, but it has not been thoroughly investigated yet. Overall, there is a gap in the literature in terms of developing alternative refrigerants for ULT refrigeration. This study aims at shedding light on this gap to direct future research in this field towards reliable, environmentally friendly and marketable alternative refrigerants.

The introduction of high-temperature heat pumps for waste heat recovery with low GWP refrigerants can reduce the greenhouse gas emissions in the industrial sector. This article evaluates the energy performance and the volumetric heating capacity of five vapour compression system configurations using n-Pentane, Butane, HCFO-1233zd(E) and HFO-1336mzz(Z) as HFC-245fa low GWP alternative fluids for heating production at temperatures of 110, 130 and 150°C and different temperature lifts. The selected architectures and the equations are presented, and the most appropriate method to calculate the intermediate pressure is selected. The results of the simulation show that single-stage cycle with an internal heat exchanger (IHX) becomes the most efficient configuration at lower temperature lifts whereas two-stage cycle with IHX at higher lifts. While n-Pentane provides the highest energy performance values, Butane (only up to 130°C) and HCFO-1233zd(E) highlight in the heating volumetric capacities. HFO-1336mzz(Z) provides intermediate values in both parameters. Consequently, the working fluid selection is highly dependent on the specifications and the energetic and installation costs.

The aim of this paper is to study the benefits of integrating CO2 trans-critical booster refrigeration system with geothermal storage. The ground is used as a heat sink for sub-cooling during the summer period and as a heat source for extracting heat in the winter season. Using field measurements from medium size supermarkets in Sweden, proposed and the existing system solutions for integrating geothermal storage in CO2 refrigeration systems are modelled and compared with standard CO2 trans-critical booster system. The techno-economical comparative analysis shows that hybrid CO2 trans-critical booster system with ground source heat pump (GSHP) as an integrated geothermal solution has 6% lower annual energy use compared to a stand-alone CO2 system with heat recovery. QC 20181105

Ponéncia presentada al 1st International Conference on Engineering Education for the XXI Century. New Competences in Engineering Education in the area of sustainability and university social responsability, celebrat a Castelló de la Plana, 6-7 de juliol de 2017 En este trabajo se expone la enseñanza de los sistemas de generación de frío mediante compresión de vapor mediante la utilización del software interactivo denominado «Frío». Se trata de un software gratuito que permite simular el comportamiento de una instalación frigorífica y que permite estudiar mejoras de eficiencia energética a implantar tanto en instalaciones existentes como en la fase de diseño. In this work the teaching of the systems of generation of cold by means of compression of steam by means of the interactive software denominated “Cold” is exposed. This is a free software that simulates the behavior of a refrigeration plant and allows to study energy efficiency improvements to be implemented in both existing installations and in the design phase.

The aim of this study is to investigate the potential of CO2 trans-critical booster refrigeration system integrated with geothermal storage to provide the cooling and the heating demands with high energy efficiency. During summer season, heat is rejected from the CO2 refrigeration system, increasing the amount of sub-cooling and storing this heat into the ground. During winter season, the heat stored in the ground is extracted and used as heat source to provide the heating requirements of the supermarket. Using field measurements data from medium size supermarkets in Sweden, existing solutions for integrated geothermal storage in a CO2 refrigeration system as well as proposal solution are modelled and compared with stand-alone CO2 trans-critical booster system. The techno-economical comparative analysis shows that hybrid CO2 trans-critical booster system with GSHP as an integrated geothermal solution has 6% lower annual energy use than a stand-alone CO2 system with heat recovery solution for refrigeration and heating in North of Europe. In addition to the computer simulations, field measurements monitoring of ten medium size supermarkets with integrated geothermal storage have been studied. Measurement system proposal guide is done to fulfill a proper energy analysis of the supermarket installation with the integrated solution. Evaluation of the missing measurements is done for the available supermarkets. One important conclusion of this part is that none of the supermarkets analyzed has enough measurement to realize a proper and comprehensive energy analysis. ISBN: 978-91-7729-513-6

[ES] Este Trabajo de Final de Grado trata sobre el diseño y la optimización de un equipo compacto compuesto por un acumulador con bomba de calor para la producción y almacenamiento de agua caliente sanitaria con una capacidad de 200 litros. Se ha prestado especial atención a la compacidad del equipo frigorífico, ya que va montado en la parte superior del acumulador, conectándose con un tubo al exterior. Se ha realizado el modelado del acumulador desde cero con Matlab® y el diseño del equipo frigorífico con el software IMST-ART®. Además, se ha elaborado un metamodelo del la bomba de calor, para ver las prestaciones en diferentes condiciones climáticas. Finalmente, se ha realizado un estudio de viabilidad económica y medioambiental, así como un posible uso como fuente de energía renovable., [CA] Aquest Treball de Final de Grau tracto sobre el disseny i l’optimització d’un equip compacte, compost per un acumulador amb bomba de calor per a la producció i emmagatzemament d’aigua calenta sanitària amb una capacitat de 200 litres. S’ha prestat especial atenció a la compacitat del equip frigorífic perquè anirà muntat en la part superior del acumulador, connectant-se amb un tub al exterior. S’ha realitzat el modelatge del acumulador des de zero amb Matlab® i el disseny del equip frigorífic amb el software IMST-ART®. A més, s’ha elaborat un metamodel de la bomba de calor, per a veure les prestacions en diferents condicions climàtiques. Per finalitzar, s’ha realitzat un estudi de viabilitat econòmica i mediambiental, així com un possible ús com a font d’energia renovable., [EN] This End of Degree Project is about the design and optimization of a compact equipment composed by an accumulator with heat pump, for the production and storage of domestic hot water with a capacity of 200 litters. It is focused on the compactness of the refrigeration equipment, which is mounted on the top of the accumulator, which connects outside with a tube. It has been done the modelling of the accumulator from scratch with Matlab® and the design of refrigeration equipment with the software IMST-ART®. It has also developed a metamodel of the heat pump to analyse the performances in different climatic conditions. Finally, it has been conducted a study of economic and environmental viability as well as a potential use as a source of renewable energy.