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While the global refrigeration capacity installed in ultra-low temperature applications is considerably lower than in standard refrigeration, the interest in such systems has risen during the last months due to their emerging demand for the preservation of mRNA vaccines. Several theoretical studies can be found in the literature for ultra-low temperature applications. However, there is still a lack of reliable experimental data that may be used for the models validation and, thereby, to perform more rigorous investigations. In light of this, the present manuscript proposes an ultra-low temperature refrigeration unit based on an indirect cascade system, developed by retrofitting a standard low-temperature R290 packaged unit. In this investigation, firstly, the suitability of the original components is assessed and, then, the unit is experimentally tested within a wide range of operating conditions. Thereby, the system's reliability is evaluated by assessing different parameters, such as discharge, condensing and evaporating temperatures and performance ratios. The main results showed a successful behaviour at the operating conditions tested, exhibiting a COP that ranged from 0.6 to 1.6 for cold room temperatures between -80 °C and -65 °C, respectively.

The natural refrigerant R744 seems to be the long term solution to be imposed in the food retail industry, where low and medium refrigeration temperatures are usually required, despite the technical difficulties related to high the pressure, especially in warm climates, leading to trans-critical operation with the consequent COP reduction. To overcome such difficulties, different approaches have been proposed in literature, being very popular the use of parallel compressor or its combination with ejector expansion devices. The efficient operation of trans-critical R744 systems requires the control of the gas cooler pressure, as well as the pressure of the flash-tank. In the case of ejector expansion devices, the ratio of entrained mass flow rate must be also included in the control variables and, at the same time, its use implies additional restrictions. The current paper presents the optimization methodology for the operating conditions of a two-stage CO2 refrigeration unit for both cases, with and without ejector. The curves of optimal combinations of gas cooler and flash-tank pressures, understood as operational control laws, are provided together with the COP achieved. The operating conditions and performance of the ejector case are compared showing COP improvements of up to 13%. The results also show that the operating region of the control variables is limited due to the use of the ejector. This study has been partially funded by the ERDF program ITC-20181143 (EJERCER) in collaboration with the company Intarcon S.L.

This work is focused on a case study of a small-scale Organic Rankine Cycle (ORC) adopted for electricity production from low-grade industrial waste heat recovery. This kind of applications raises a great interest due to the high amount of low-grade waste heat recoverable within industrial processes, but lacks of in-depth experimental investigations on the topic. The main reason is the difficulty to reach profitable small-scale projects, so more cost-effective solutions are being explored in the literature through thermo-economic optimizations. Nonetheless, the results obtained cannot be discussed with respect to actual operating data. In light of this, this paper proposes to conduct the thermo-economic optimization on the basis of an experimental application. In this manner, a comprehensive model of the facility is developed, calibrated, and validated from actual operating data. The model is used to conduct the thermo-economic optimization, revealing the influence of the organic fluid, cycle architecture, geometric parameters of main components, or control strategy used to obtain the best cost-effective solution. The main results show that, by means of a multivariable optimization using cost-effective ratios as objective function, a cheaper and powerful solution adapted to each specific project may be designed.

Europe is encouraging new buildings to minimize their primary energy dependence to be considered, from 2021, Nearly Zero Energy Buildings (NZEB). In this regard, solar thermal energy is being extensively used as a renewable source to produce Domestic Hot Water (DHW). However, solar thermal energy fields may be oversized during the warmest season of the year, rejecting the waste heat to the ambient while increasing the air conditioning demand. The Solar-driven Ejector Refrigeration System (SERS) may be a solution for solar cooling. Nevertheless, the SERS performance is constrained when low to medium temperature solar thermal collectors, commonly installed for DHW production, are used in warm climates. Consequently, this paper reformulates the SERS application as a novel fresh air pre-cooling system for air handling units. Thereby, greater evaporating temperatures that enable the SERS adoption in NZEB are explored. In doing so, the seasonal performance under severe operating conditions is analyzed considering the two-phase flow ejector geometry, as well as refrigerants with low global warming potential. Main results demonstrate a maximum seasonal COP of 0.37 by using R717. Moreover, an average cooling capacity of 28.3 kW could be produced per kW of electricity if an optimized multi-ejector solution with R600 is adopted.

Environmental restrictions on the use of fluorinated refrigerants are turning the attention to natural solutions. Ammonia is historically proven as a refrigerant that requires low purchasing costs, has superior thermodynamic properties, and exhibits great values of coefficient of performance. Therefore, considering ammonia safety issues, solutions able to prevent leakages and minimize the charge of refrigerant are kind of welcomed. This paper conducts an investigation focused on the experimental analysis of the refrigerant charge and performance of a novel ultra-low charge air-cooled packaged chiller for medium temperature industrial applications. The unit is developed using emerging technology to reduce the amount of ammonia charge, such as the microchannel condenser, semi-hermetic screw compressor, miscible lubricant, single-stage oil separator, and dry-expansion plates heat exchanger. In doing so, the empirical adjustment of the ammonia charge revealed that there is an optimum that maximizes the coefficient of performance and the cooling capacity of the system. A charge capacity ratio of 75 g/kW was achieved for a unit with a rated cooling capacity of 230 kW and a gross coefficient of performance of 2.3, i.e, a reduction of 50% in the specific charge and an improvement of 20% in the performance, with regard to the systems in the market. Moreover, the system performance, such as operating temperatures, evaporator effectiveness, and oil return, are assessed for a wide range of conditions and compressor rotational speeds.

In the present work, a thermo-economic evaluation of the low global warming potential fluids HCFO-1233zd-E, HFO-1336mzz-Z and HFO-1234ze-Z as alternatives to HFC-245fa in organic Rankine cycle systems for low temperature heat sources is carried out. A thermodynamic organic Rankine cycle model is extended with the overall cost of the system, and it is used to identify the system parameter values for each working fluid considered that minimize the specific investment cost at a given set of the heat source and sink inlet temperatures. Thereby, the results show that HCFO-1233zd-E and HFO-1336mzz-Z present higher efficiencies than HFC-245fa, while HFO-1234ze-Z presents lower efficiency than HFC-245fa. The low global warming potential working fluids result in lower specific investment cost values than HFC-245fa. HFO-1336mzz-Z presents the lowest specific investment cost and highest efficiency values among the working fluids of interest throughout the range of operating conditions studied.

This paper compares the predicted organic Rankine cycle performance of two low global warming potential working fluids, R1234yf and R1234ze, alternatives to R134a over a wide range of evaporating temperatures and condensing temperatures for a given thermal power input. The results show that R1234yf would require 18.3% to 25.8% higher pump power and would enable up to 13.9% lower net cycle efficiencies than R134a over the range of cycle conditions examined in this work. In the other hand, R1234ze would require 15.7% to 20.2% lower pump power and would enable up to 13.8% higher net cycle efficiencies than R134a, over the range of cycle conditions analyzed. Both alternative fluids net cycle efficiency is benefitted substantially by a recuperator. The differences with R134a in net cycle efficiency are accentuated for high evaporating and condensing temperatures.

Supermarkets are recognized worldwide as great energy consumers, especially in developed countries. Typically, energy consumptions are due to cold, heat and electricity requirements. So a Combined Cold, Heat and Power (CCHP) system (also called trigeneration system) can be used to reduce energy demands and, hence, greenhouse gas emissions to the atmosphere. In this way, this work proposes a small-scale Organic Rankine Cycle (ORC) CCHP application in a supermarket. The ORC has been designed to be used with a biomass boiler, and to produce electricity and useful heat at two different temperature levels related to an absorption chiller and supermarket heating demand. With this in mind, this work conducts the experimental characterization of the CCHP system in a test bench. Thereby, the experimental results obtained are used to predict the expected performance of the system under the supermarket conditions, as well as to quantify the energy, environmental and economic benefits of the application.

The GWP limitations are being progressively introduced in Europe through Regulation EU No 517/201, phasing out R134a in most of its refrigeration and air conditioning applications. Pure hydrofluoroolefins are proposed to substitute this fluid, however generally system modifications are needed to achieve a good performance. In the case of R1234ze(E), the cooling capacity is always much below that of R134a in drop-in or light retrofit substitutions. This work performs an experimental comparison using R1234ze(E) and R134a under different refrigeration operating conditions. R1234ze(E) is tested considering the use or not of an internal heat exchanger, and R134a at the same or lower compressor rotation speed. Results show that the use of R1234ze(E) with an open-type compressor 43% larger and an internal heat exchanger of 25% effectiveness, leads to a cooling capacity augmentation, enough to reach R134a cooling capacity in the different conditions tested. For R450A, it is sufficient only with the IHX activation.

Refrigeration industry is adopting a proactive strategy to phase out fluorinated greenhouse gases by more sustainable working fluids. R744 is a natural refrigerant widely proposed for commercial refrigeration. Its use in cascade and booster cycles allows a combined cooling and freezing production. However, when single-stage evaporation at low temperature is required, the adoption of R744 in transcritical cycles is scarce. The main reasons are due to the low Coefficient of Performance (COP) achieved, as well as the technical limitations to reach extreme pressure ratios using commercial compressors. In light of this, this paper proposes to use the CO2 Ejector-Expansion Refrigeration Cycle (EERC) to overcome these drawbacks. To assess the feasibility of the proposal, a thermoeconomic optimization is conducted for low-temperature refrigeration in warm climates. The analysis has been conducted considering a two-phase flow ejector, a commercial double-stage compressor, and evaporating conditions ranging from −10 °C to −38.11 °C, which was revealed the minimum temperature to avoid the triple point inside the ejector. The results showed that the EERC allows using smaller commercial compressors within a broader operating envelope, improving the annual average COP about 5.5% compared to the reference cycle, besides reducing investment and yearly energy consumption costs. This study has been partially funded by the ERDF program ITC-20181143 (EJERCER) in collaboration with the company Intarcon S.L.

Stricter emission regulations and variability of fuel prices pose the focus on the optimization of steam turbine based propulsion plants of Liquefied Natural Gas (LNG) ships. The efficiency of such a propulsion plant has been improved in this work by studying the introduction of reheating and preheating stages in the onboard regenerative Rankine cycle. A thermodynamic model of the propulsion plant has been developed from the facility diagrams, being validated afterwards with available experimental data from actual ship operation. The predictions of different scenarios obtained by the model when introducing modifications in the power propulsion cycle showed promising results. It was found that a combination of preheating and reheating stages was found to increase the cycle efficiency up to 33.71%, reducing fuel consumption in around 20 t/day and CO 2 emissions in more than 20,000 t per year. An exergy analysis of the impact of cycle modifications and an economic assessment of the proposed investment plan were performed. It was found that the boiler was the main contributor to exergy destruction, fact that justifies the cycle modifications performed. The economic analysis of the investment plan of implementing the selected alternative provided benefits even in a conservative scenario, with an Internal Rate of Return higher than 12% and a Pay-Back Period less than 9 years for all the studied scenarios. In summary, a practical industrial application of thermodynamic and exergy analysis to the propulsion plant of a LNG ship has been shown, allowing an efficiency, economic and environmental improvement.

[EN] The limited availability of drugs registered for dairy goats makes veterinarians prescribe off-label treatments with a legally established minimum safety period of seven days. The aim of this work was to verify if the exceptional use of macrolide antibiotics in dairy goats generates residues in milk and cheeses within that period. Hence, three macrolide drugs (erythromycin, tylosin and spiramycin) were administred in an in vivo experiment in dairy goats. Ripened cheeses were made from bulk milk obtained before drug administration, 24¿h after treatment, and at the end of the recommended withdrawal period. Residual amounts of erythromycin (234.9¿±¿52.7¿¿g/kg), tylosin (198.7¿±¿57.8¿¿g/kg) and spiramycin (1539.8¿±¿469.4¿¿g/kg), widely exceeding their legal maximum residue limits (MRLs) established, were detected in milk collected 24¿h after treatment, making the cheese production in most cases impossible. After the seven-day period, only spiramycin was detected in goat¿s milk (79.6¿±¿19.2¿¿g/kg) although no antibiotic residues were found in the cheeses. A withdrawal time of seven days seems suitable to guarantee milk safety after the administration of erythromycin and tylosin without any negative effects neither on the milk nor on the and cheese properties. However, given the rapid elimination of these substances, a shorter withdrawal period might be considered. For spiramycin, persisting in milk for a longer period, further studies on its pharmacokinetics in dairy goats would be recommendable to avoid a potential risk to consumer health., This work is part of the AGL-2013-45147-R funded by Ministerio de Ciencia e Innovacion (Madrid. Spain). The authors thank the 'Program of Support for Research and Development' (PAID-2014, UPV) for support P. Quintanilla PhD studies at Universitat Politecnica de Valencia.

Due to the adoption of EU Regulation No 517/2014, R404A is going to be banned in Europe in most of refrigeration applications, in which is typically used, due to its very high GWP value, 3943. In this paper an experimental comparison between R404A and R448A, a non-flammable alternative with GWP of 1390, is presented. The experimental tests are intended to simulate typical freezing and conservation temperatures and different condensing conditions. Despite cooling capacity of R448A is slightly below that of R404A, R448A energy consumption is even smaller; and R448A COP is higher than that obtained using R404A. Hence, it can be concluded that R448A could be an energy efficient alternative to R404A with a GWP reduction of 70%. Compressor discharge temperature remains at non-dangerous levels., The authors thankfully acknowledge "Ministerio de Educacion, Cultura y Deporte - Gobierno de Espana" (Grant Number FPU12/02841) for supporting this work through "Becas y Contratos de Formacion de Profesorado Universitario del Programa Nacional de Formacion de Recursos Humanos de Investigacion del ejercicio 2012".

A combined organic Rankine cycle and vapor compression cycle (ORC-VCC) system activated by low temperature heat sources was studied. Two low GWP fluids were considered as working fluids for the VCC and two different low GWP fluids for the ORC. System performance was evaluated through computational modeling over different operating conditions. The computed thermal COP of the ORC-VCC system varied between 0.30 and 1.10 over the range of operating conditions studied. The computed electrical COP of the ORC-VCC system, defined as the ratio of the rate of cooling and the ORC pump power consumption, varied between 15 and 110. The choice of VCC working fluid had only a limited influence on system thermal or electrical efficiency, with HFO-1234ze(E) presenting slightly better results. Use of HFO-1336mzz(Z) as the ORC working fluid resulted in slightly higher system thermal efficiencies and significantly higher system electrical efficiencies throughout the range of operating conditions studied. Furthermore, the system is evaluated for a typical application and the feasibility study shows good economical results., The authors thankfully acknowledge DuPont Corporation for supporting this work.

[EN] This work conducts an experimental characterization of an Organic Rankine Cycle (ORC) module along the operating conditions expected for micro Combined Heat and Power (CHP) applications. For this, a monitored test bench has been used and adapted to the planned test procedure, which consisted of varying the condensing conditions for a fixed low grade heat source. Thereby, 10 steady state points are achieved and analyzed according to thermal power input, useful heat production, gross and net electrical powers, electrical and thermal cycle efficiencies and expander effectiveness parameters. The results show the importance, for all the cited parameters, that takes to operate with a suited pressure ratio, associated with the expander built-in volume ratio, to each specific application. So, if the useful heat temperature requirements allow to operate with a moderate under-expansion in the expander, the module is optimized., The authors want to acknowledge all the invaluable cooperation of Rank (R), the ORC manufacturer, for its support in this project. Also to thank greatly the Jaume I University for its financial support under the PhD grant PREDOC/2013/28 of "Convocatoria d'ajudes predoctorals per a la formacio de personal investigador del Pla de promocio de la investigacio de la Universitat jaume I de Castello (Spain)".

This thesis focuses on the use of small-scale Organic Rankine Cycles (ORC) to produce electricity from low-grade waste heat recovery of industrial processes. In particular, a thermo-economic (combination of thermodynamic and economic) optimization is conducted to achieve more cost-effective systems and, thus, to contribute to the ORC adoption in practical applications. As a novelty, this investigation is based on an experimental application case, which allows developing a comprehensive model of the system and its subsequent validation from actual data. Thereby, more realistic results are reached, which underline the most relevant topics to pay attention to improve the economic feasibility of new projects., Esta tesis se centra en el uso de sistemas de pequeña escala basados en el ciclo Rankine orgánico (ORC por las siglas en ingles) para la producción de electricidad a partir de la recuperación de calor residual de baja temperatura en procesos industriales. En concreto, se lleva a cabo una optimización termoeconómica (combinación entre termodinámica y económica) como método para mejorar la rentabilidad de los proyectos y, de esta forma, favorecer el uso de los sistemas ORC en aplicaciones prácticas. Como novedad, la investigación se lleva a cabo en torno a un caso experimental de aplicación, lo que permite desarrollar un modelo íntegro del sistema y posteriormente validarlo con datos reales. De este modo, se alcanzan resultados más realistas que ponen de relieve los aspectos clave para mejorar la viabilidad económica de nuevos proyectos.

An experimental evaluation of HFO-1336mzz-Z as a low global warming potential working fluid for ORC systems in micro-scale low temperature applications has been conducted. The energy performance in a fully monitored ORC module has been analyzed varying the heat source temperatures between 140 °C and 160 °C and heat sink temperatures between 25 °C and 40 °C. The ORC module uses a regenerative configuration allowing heat recovery not only from the heat source but also from the expanded vapor, thus improving the cycle thermal and electrical efficiency. The maximum gross electrical power generated was 1100 W, while the net electrical efficiency ranged from 5.5% to 8.3%. The volumetric expander performance was analyzed by means of the filling factor, while deviations of expander operation from ideal performance were evaluated by means of the isentropic and overall expander-generator efficiency. Net electrical efficiency, isentropic expander efficiency and volumetric expander performance obtained with HFO-1336mzz-Z in this work are higher than those obtained with HFC-245fa in a previous work using the same experimental facility.

Nowadays, a high amount of industrial thermal energy is still lost due to the lack of competitive solutions for energy revalorization. Facing this challenge, this paper presents a novel technology, based on a reversible High-Temperature Heat Pump (HTHP) and Organic Rankine Cycle (ORC). The proposed system recovers low-grade waste heat to generate electricity or useful heat in accordance with consumer demand. Compressor and expander semi-empirical models have been considered for the reversible system computational simulation, being HFC-245fa the working fluid selected. The built-in volume ratio and Internal Heat Exchanger (IHX) effectiveness have been optimized to reach the maximum energy efficiency in each operating condition. Although HFC-245fa exhibits energy performance attributes, its high Global Warming Potential (GWP) is an issue for climate change mitigation. Hence, multi-objective optimisation of the environmentally friendly working fluids Butane, Pentane, HFO-1336mzz(Z), R-514A, HCFO-1233zd(E) and HCFO-1224yd(Z) has been carried out. The results show that the system proposed, working with HFC-245fa, achieves a Coefficient of Performance (COP) of 2.44 for condensing temperature of 140 °C, operating in HTHP mode, whereas the ORC mode provides a net electrical efficiency of 8.7% at condensing temperature of 40 °C. Besides, HCFO-1233zd(E) and HCFO-1224yd(Z) are both appropriate alternatives for the HFC-245fa replacement. These working fluids provide a COP improvement of 9.7% and 5.8% and electrical net efficiency improvement of 2.1% and 0.8%, respectively, compared to HFC-245fa. This paper provides a reference study for further designs and developments of reversible HTHP-ORC systems used for industrial low-grade waste heat recovery.

This work is focused on waste heat recovery of jacket cooling water from Internal Combustion Engines (ICEs). Cooling water heat does not always find use due to its low temperature, typically around 90 °C, and usually is rejected to the ambient despite its high thermal power. An efficient way to take benefit from the ICE cooling water waste heat can be to increase the power output through suitable bottoming Organic Rankine Cycles (ORCs). Thereby, this work simulates six configurations using ten non flammable working fluids and evaluates their performances in efficiency, safety, cost and environmental terms. Results show that the Double Regenerative ORC using SES36 gets the maximum net efficiency of 7.15%, incrementing the ICE electrical efficiency up to 5.3%, although requires duplicating the number of main components and high turbine size. A more rigorous analysis, based on the system feasibility, shows that small improvements in the basic cycle provide similar gains compared to the most complex schemes proposed. So, the single Regenerative ORC using R236fa and the Reheat Regenerative ORC using R134a seem suitable cycles which provide a net efficiency of 6.55%, incrementing the ICE electrical efficiency up to 4.9%.

[EN] In this work an experimental evaluation of the working fluid HCFO-1233zd-E as HFC-245fa replacement in ORC systems for low temperature heat sources has been conducted. A fully monitored ORC module has been used to test both working fluids at different operating conditions. Due to the different densities of the working fluids, the mass flow rate for HCFO-1233zd-E is approximately 20% lower than for HFC-245fa. This causes thermal and electrical powers to be lower for HCF0-1233zd-E than for HFC245fa. However, net electrical efficiency is similar for both working fluids, ranging from 5% to 9.7% in the tested operating conditions. Regarding the expander performance, various performance indicators are addressed. The expander isentropic performance has a maximum value of 75%, with higher values for HCFO-1233zd-E than for HFC-245fa. The overall efficiency of the expander, similar for both working fluids, ranges from 44% to 57% in the experimental test range. (C) 2016 Elsevier Ltd. All rights reserved., The authors thankfully acknowledge the cooperation of Rank (R) for its support in this project.

[EN] Climate change is demonstrated through global surface temperatures increase in the last century. To stop this phenomenon, new regulations that ban or tax greenhouse gas fluids (HFC among them) have been approved. In the medium term, only low-GWP refrigerants will be permitted in developed countries. HFO fluids and most used HFCs as refrigerants in HVACR systems possess similar thermophysical properties. Among them, one of the most promising is R1234ze(E). This refrigerant presents good environmental properties and can be used in most of HVACR applications, pure or mixed with HFC or natural refrigerants (mainly CO2). This paper collects the most relevant research about R1234ze(E) thermophysical and compatibility properties, heat transfer and pressure drop characteristics, and vapor compression system performance; separating those works that consider R1234ze(E) pure or blended. Once the available literature is analyzed, it can be concluded that pure R1234ze(E) is a good option only in new HVACR systems. Nevertheless, if it is combined with other refrigerants, the final GWP value is also considerably reduced, maintaining efficiency parameters at levels that allow them to replace R134a, R404A or R410A in existing systems with minor modifications., The authors thankfully acknowledge the “Ministerio de Educación, Cultura y Deporte” (Grant Number FPU12/02841) for supporting this work through “Becas y Contratos de Formación de Profesorado Universitario del Programa Nacional de Formación de Recursos Humanos de Investigación del ejercicio 2012”.

This paper explores the relationship between infectious and non-infectious herd factors with the occurrence of pneumonia at slaughter and productive parameters in fattening pigs on 39 fattening herds. A questionnaire was used to obtain environmental and management factors (non-infectious factors). Blood samples and lungs were obtained from 35 pigs in each herd at slaughter. Serological testing was performed for antibodies against three respiratory pathogens (infectious factors): porcine reproductive and respiratory syndrome virus (PRRSV), Mycoplasma hyopneumoniae (Mh) and Aujeszky's disease Virus-gE protein (ADV-gE). Lung lesion classifications were catarrhal-purulent bronchopneumonia (CPBP), pleuropneumonia (PLP) and pleuritis. A mean lesion value (MLV) was calculated for each lesion. ANOVA and logistic regression assessed statistical associations among MLV, average daily gain (ADG) and feed conversion ratio (FCR) (dependent variables) with infectious and non-infectious factors (independent variables). Mh vaccination was associated with a significant decrease in CPBP; high Mh seroprevalences was associated with an increased level of CPBP. FCR was negatively related with high seroprevalences for ADV-gE and Mh. No significant associations were seen for ADG.

The IHX (internal heat exchanger) is introduced in some refrigeration systems in order to achieve higher energy performances. Results obtained vary greatly depending on the refrigerant used and working conditions. This paper describes a drop-in analysis of IHX effects on the performance of a vapour compression system using R1234ze(E) and R450A (R134a/R1234ze(E) commercial mixture) as R134a low-GWP replacements. The tests were carried out in a completely monitored vapour compression system varying the condensing and evaporating temperature, with and without a counter-current flow tube-in-tube IHX. Because the cooling capacity rises and the power consumption remains similar, the conclusion is that the IHX has a positive influence on the energy efficiency for all refrigerants tested. The COP (coefficient of performance) gain using R1234ze(E) is the highest observed (overcomes the R134a COP for the same conditions). The R1234ze(E) and R450A discharge temperature increments are lower than those of R134a so does not reach dangerous values and the IHX pressure drops are also below than that of R134a., The authors thankfully acknowledge "Ministerio de Educacion, Cultura y Deporte - Gobierno de Espana" (Grant number FPU12/02841) for supporting this work through "Becas y Contratos de Formacion de Profesorado Universitario del Programa Nacional de Formacion de Recursos Humanos de Investigacion del ejercicio 2012".

[EN] Commercial Refrigeration comprises food freezing and conservation in retail stores and supermarkets, so, it is one of the most relevant energy consumption sectors, and its relevance is increasing. This paper reviews the most recent developments in commercial refrigeration available in literature and presents a good amount of results provided these systems, covering some advantages and disadvantages in systems and working fluids. Latest researches are focused on energy savings to reduce CO2 indirect emissions due to the burning of fossil fuels. They are focused on system modifications (as dedicated subcooling or the implementation of ejectors), trigeneration technologies (electrical, heating and cooling demand) and better evaporation conditions control. Motivated by latest GWP regulations that are intended to reduce high GWP HFC emissions; R404A and R507 are going to phase out. Besides hydrocarbons and HFO, CO2 appears as one of the most promising HFC replacements because its low contribution to global warming and high efficiencies when used in transcritical and low-stage of cascade systems., The authors thankfully acknowledge "Ministerio de Educacion, Cultura y Deporte" for supporting this work through "Becas y Contratos de Formacion de Profesorado Universitario del Programa Nacional de Formacion de Recursos Humanos de Investigacion del ejercicio 2012".

This paper deals about an experimental application of an ORC (organic Rankine cycle) in a ceramic industry for low grade waste heat recovery. The ORC module used in this application was initially designed and constructed to satisfy the main specifications for an efficient power system, highlighting a volumetric expander with large built-in volume ratio. Furthermore, the performance of the ORC was experimentally characterized in a test bench in a previous work, achieving a maximum gross electrical efficiency of 12.32%. Taking this as a starting point, the aim of this work is to verify the performance of this ORC operating in actual industrial conditions, besides to profiting the information extracted from the application to assess its profitability. For this, the system performance is experimentally characterized in the industry, discussing and comparing the results obtained to laboratory data. From these experimental results a model of the system is developed, which allows predicting the net electrical production of the system along a typical year of operation and quantifying the energy and environmental benefits of the project. Moreover, from the electrical generation, investment costs required and industrial electricity price, a feasibility study is conducted to address the profitability of the application., The authors are indebted to the Minister of industry of 'Generalitat Valenciana' (Spain) for its financial assistance under project INIDIV2010022 and Rank (R), the ORC manufacturer, for its support in this project. Also to thank greatly the Jaume I University for its financial support under the PhD grant PREDOC/2013/28 of 'Convocatoria d'ajudes predoctorals per a la formacio de personal investigador del Pla de promocio de la investigacio de la Universitat Jaume I de Castello (Spain)'.

An ORC (organic Rankine cycle) module, designed and built for a specific CHP (combined heat and power)) application, is tested in this paper. The aim of the work is to characterize the system performance in the operating range allowed by the ORC. For this purpose, a test procedure has been conducted in a test bench. The heat source has been simulated through a natural gas boiler and a thermal oil heat transfer loop to control the temperature in the low grade range of 90 °C 150 °C. The heat sink has been developed using a dry cooler to control the hot water temperature in the range of 30 °C, corresponding to a power application, to 80 °C, of a small-scale CHP application that provides hot water at 90 °C. Thereby, the results show that the thermal power captured by the ORC, electricity and useful heat produced, increase with the rise of the thermal oil temperature and larger pressure ratios. Moreover, the expander electrical isentropic effectiveness is maximized about 70% for a pressure ratio suitable for a CHP system. The cycle efficiency slightly continues increasing for higher pressure ratios, up to a net electrical efficiency of about 8%., The authors want to acknowledge all the invaluable cooperation of Rank (R), the ORC manufacturer, for its support in this project. Also to thank greatly the Jaume I University for its financial support under the PhD grant PREDOC/2013/28 of 'Convocatoria d'ajudes predoctorals per a la formacio de personal investigador del Pla de promocio de la investigacio de la Universitat Jaume I de Castello (Spain)'.

[EN] The EU Regulation No 517/2014 is going to phase-out most of the refrigerants commonly used in refrigeration and air conditioning systems (R134a, R404A and R410A) because of their extended use and their high GWP values. There are very different options to replace them; however, no refrigerant has yet imposed. In this paper we review and analyze the different mixtures proposed by the AHRI as alternative refrigerants to those employed currently. These mixtures are composed by HFC refrigerants: R32, R125, R152a and R134a; and HFO refrigerants: R1234yf and R1234ze(E). It is concluded, from the theoretical analysis, that most of the new HFO/HFC mixtures perform under the HFC analyzed (although some experimental studies show the contrary) and, in most cases, do not meet the GWP restrictions approved by the European normative. Furthermore, some of the mixtures proposed would have problems due to their flammability., The authors thankfully acknowledge "Ministerio de Educacion, Culture y Deporte" (Grant number FPU12/02841) for supporting this work through "Becas y Contratos de Formacion de Profesorado Universitario del Programa Nacional de Formacion de Recursos Humanos de Investigacion del ejercicio 2012".

In this paper the performance of an Organic Rankine Cycle (ORC) module, which was designed and built for a specific power application, is experimentally characterized. The ORC tested satisfies the main specifications for an efficient power system, highlighting a volumetric expander with large built-in volume ratio. For tests development, a monitored test bench has been used and adapted to the planned test procedure, which consisted of varying the thermal power input for different condensing conditions. Thereby, 10 steady state points are achieved and analyzed according to thermal power input, gross and net electrical powers, electrical cycle efficiencies and expander effectiveness. The results show that the ORC performances are improved for higher thermal oil temperatures, capturing more thermal power, producing more electricity and achieving better cycle efficiencies. The maximum gross electrical efficiency obtained is 12.32%, for a heat source temperature about 155 °C and a direct dissipation to the ambient. Moreover, the expander reaches an electrical isentropic effectiveness about 65% for an optimum pressure ratio around 7, being a suitable system for power applications from low grade heat sources., The authors are indebted to the Minister of Industry of 'Generalitat Valenciana' (Spain) for its financial assistance under project INIDIV2010022 and Rank (R), the ORC manufacturer, for its support in this project. Also to thank greatly the Jaume I University for its financial support under the PhD grant PREDOC/2013/28 of 'Convocatoria d'ajudes predoctorals per a la formacio de personal investigador del Pla de promocio de la investigacio de la Universitat Jaume I de Castello (Spain)'.

R1234yf and R1234ze(E) have been proposed as alternatives for R134a in order to work with low GWP refrigerants, but this replacement results generally in a decrease of the performance. For this reason, it is interesting to explore ways to improve the system performance using these refrigerants. In this paper, a comparative study in terms of energy performance of different single stage vapour compression configurations using R1234yf and R1234ze(E) as working fluids has been carried out. The most efficient configuration is the one which uses an expander or an ejector as expansion device. On the other hand, using an internal heat exchanger in a cycle which replaces the expansion valve by an expander or an ejector could produce a detrimental effect on the COP. However, for all the configurations the introduction of an internal heat exchanger produces a significant increment on the cooling capacity.

Six refrigerants are evaluated as low GWP replacements for R404A using different configurations, including two-stage system architectures. These refrigerants are selected according to similar characteristics to R404A, and they are the mid-term alternatives R407A and R407F, and the long-term alternatives: L40 and DR-7 (with very low GWP and low flammability), N40 and DR-33 (with low GWP and no flammability). In order to have a complete comparison range, various operating conditions are considered, covering low and medium evaporator temperatures and two levels of condensation temperatures. Configurations selected are presented and the equations used to simulate the expected performance are shown. From a given cooling capacity, volumetric flow rate and COP are compared, taking R404A as baseline. The most efficient alternatives are the low-flammable refrigerants, L40 and DR-7, and when no flammability is acceptable, N40 and DR-33 are also very good options., The authors thankfully acknowledge "Ministerio de Educacion, Cultura y Deporte" for supporting this work through "Becas y Contratos de Formacion de Profesorado Universitario del Programa Nacional de Formacion de Recursos Humanos de Investigacion del ejercicio 2012" The authors also want to acknowledge Honeywell International Inc. for supporting this work.

[EN] HFC-245fa is a common working fluid used in Organic Rankine Cycles generating mechanical power from low temperature heat. This paper compares the predicted ORC performance of two novel low GWP working fluids, HCFO-1233zd-E and HFO-1336mzz-Z, to HFC-245fa over a wide range of evaporating temperatures, condensing temperatures and vapour superheat values. Expander power output, required pump power input, net cycle efficiencies, mass flow rates and turbine size parameters with HCFO-1233zd-E, HFO-1336mzz-Z and HFC-245fa were compared for a given thermal power input. HCFO-1233zd-E and HFO-1336mzz-Z are predicted to have attractive thermodynamic Rankine power cycle performance. HCFO-1233zd-E would require 10.3%-17.3% lower pump power and would enable up to 10.6% higher net cycle efficiencies than HFC-245fa over the range of cycle conditions examined in this paper. The turbine size required with HCFO-1233zd-E would be up to about 7.5%-10.2% larger than with HFC-245fa. HFO-1336mzz-Z would require 36.5%-41% lower pump power and would enable up to 17% higher net cycle efficiencies than HFC-245fa over the range of cycle conditions examined in this paper. The turbine size required with HFO-1336mzz-Z would be up to about 30.9%-41.5% larger than with HFC-245fa. HFO-1336mzz-Z cycle efficiency is benefitted substantially by a recuperator. The net cycle efficiency increases and the required turbine size decreases relative to HFC-245fa for HCFO-1233zd-E and for HFO-1336mzz-Z at higher evaporating and condensing temperatures. (C) 2014 Elsevier Ltd. All rights reserved., The authors thankfully acknowledge DuPont Corporation for supporting this work

[EN] This work presents an experimental analysis of a non-flammable R1234ze(E)/R134a mixture (R450A) as R134a drop-in replacement. While R134a has a high GWP value (1430), the R450A GWP is only 547. The experimental tests are carried out in a vapour compression plant equipped with a variable-speed compressor. The replacement suitability has been studied combining different operating conditions: evaporation temperature, condensation temperature and the use of an internal heat exchanger (IHX). The drop-in cooling capacity of R450A compared with R134a is 6% lower as average. R450A COP is even higher to those resulting with R134a (approximately 1%). The discharge temperature of R450A is lower than that of R134a, 2K as average. The IHX has a similar positive influence on the energy performance of both fluids. In conclusion, R450A can be considered as a good candidate to replace R134a., The authors thankfully acknowledge "Ministerio de Educacion, Cultura y Deporte" for supporting this work through "Becas y Contratos de Formacion de Profesorado Universitario del Programa Nacional de Formacion de Recursos Humanos de Investigacion del ejercicio 2012".

[EN] This paper presents an energy performance evaluation of two low-GWP refrigerants, R1234yf and R1234ze(E), as drop-in replacements for R134a. Tests are carried out in a monitored vapor compression system combining different values of evaporation and condensation temperature, and without/with the adoption of an internal heat exchanger. The parameters analyzed are volumetric efficiency, cooling capacity and COP and they are presented taking R134a as baseline. Results show that without IHX the average volumetric efficiency for R1234yf and R1234ze is 4% and 5% lower compared with R134a. The cooling capacity obtained with R1234yf and R1234ze is reduced, with an average difference of 9% and 30% without IHX. Also, COP values are about 7% lower for R1234yf and 6% lower for R1234ze than those obtained using R134a. Finally, the use of an internal heat exchanger reduces the COP differences for both replacements. (C) 2014 Elsevier Ltd. All rights reserved., The authors thankfully acknowledge "Ministerio de Educacion, Cultura y Deporte" for supporting this work through "Becas y Contratos de Formacion de Profesorado Universitario del Programa Nacional de Formacion de Recursos Humanos de Investigacion del ejercicio 2012".

This work presents a model of a shell-and-tube evaporator using R1234yf and R134a as working fluids. The model uses the effectiveness-NTU method to predict the evaporation pressure and the refrigerant and secondary fluid temperatures at the evaporator outlet, using as inputs the geometry of the evaporator, the refrigerant mass flow rate and evaporator inlet enthalpy, and the secondary fluid volumetric flow rate and evaporator inlet temperature. The model performance is evaluated using different two-phase flow heat transfer correlations through model outputs, comparing predicted and experimental data. The output parameter with maximum deviations between the predicted and experimental data is the evaporating pressure, being the deviations in outlet temperatures less than 3%. The evaporator model using Kandlikar's correlation obtains the highest precision and the lowest absolute mean error, with 4.87% in the evaporating pressure, 0.45% in the refrigerant outlet temperature and 0.03% in the secondary fluid outlet temperature.

A moving-boundary dynamic model of a shell-and-tube condenser is presented. Within this approach, the mean void fraction is a relevant parameter which is obtained, in this work, using different correlations proposed in the literature for the flow pattern analyzed. In order to evaluate the performance of the model with each different mean void fraction correlation, a set of experimental tests using R134a as working fluid, varying the main operating variables (refrigerant mass flow rate, secondary fluid mass flow rate and inlet temperature), are performed. The model performance is analyzed from the system model outputs, namely, condensing pressure and refrigerant and secondary fluid outlet temperatures. The results, comparing model predictions and experimental data, show the great influence of the mean void fraction correlation on the model predictions with noticeable discrepancies depending on the correlation used. It is also observed that the model using the homogeneous correlation frequently provides acceptable results in all the tests analyzed, although the most appropriate correlation depends on the transient characteristics.

Condemnation causes of growth retarded pigs were studied in a Spanish abattoir. A total of 513 carcasses out of 6017 (8.5%) were rejected during inspection. The main reasons for condemnation were abscesses, cachexia, catarrhal bronchopneumonia, vertebral osteomyelitis, arthritis, pleuritis, peritonitis and pleuropneumonia. Positive relationships were found between tail lesions and arthritis (OR = 5.23) or vertebral osteomyelitis (OR = 24.81), while no relationships were found between tail lesions and abscesses. Lower risks were observed among carcasses condemned for cachexia, and were as follows: abscesses (OR = 0.18), arthritis (OR = 0.32), vertebral osteomyelitis (OR = 0.06). Arcanobacterium pyogenes, either alone or in combination with other agents, was the main bacterial species isolated from abscesses, osteomyelitis and arthritis (73.5%, of lesions). Direct economical losses associated with condemnation were calculated to be is an element of 30,000. (c) 2006 Elsevier Ltd. All rights reserved.

A seven-year-old female Indian python ( Python molurus ) weighing about 35 kg was euthanased after several clinical episodes of stomatitis, pneumonia, ophthalmitis and dystocia over a period of four years. The animal had been maintained in a terrarium in a circus truck at an adequate temperature. During shows, however, the snake was considered to be exposed to stressful conditions for several hours at a time at low temperatures and with noise and bright lights. A post-mortem examination indicated ulcerative stomatitis, osteomyelitis, severe pneumonia and numerous granulomata and multifocal necrosis in stomach and spleen. Corynebacterium macginleyi was isolated in pure culture from the ulcerative stomatitis, and mixed with Stenotrophomonas maltophilia from the lungs and spleen. The findings indicated that the snake had died from a septicaemic process caused by C. macginleyi , probably originating from the stomatitis. The role of S. maltophilia as a secondary agent is discussed. The stress of the circus show and poor husbandry may have predisposed the animal to infection and septicaemia. This is the first report of C. macginleyi causing disease in a snake.