Renewable and waste heat applications for heating, cooling, and power generation based on advanced configurations

Using renewable heat energy sources, recovering the waste heat, and enhancing the processes and energy efficiency can reduce the electricity dependency of several industrial applications. Renewable and waste heat have a low-grade enthalpic level and should be combined with other technologies to bring it to a practical level. This could be achieved by increasing the variety of heat sources and their combinations (multi-function systems), resulting in a high overall energy performance and reducing greenhouse gas emissions. Recent research on this topic has been conducted considering solar-assisted geothermal heat pumps (single and combined), low-grade waste heat, organic Rankine-vapour compression cycles (ORC-VCC), and absorption refrigeration. In the current research, comprehensively review of the state-of-the-art advanced arrangements using renewable heat sources and waste heat utilisation for simultaneous heating, cooling, and power generation was performed. To the best of the author’s knowledge, the use of waste heat from VCC systems represents one of the most promising technologies in the future. Solar and geothermal heat pumps are considered for different applications and at different temperatures, presenting a high coefficient of performance. However, their utilisation is beneficial only when both renewable heat sources are considered. Although both the ORC and ejector refrigeration systems demonstrated low thermal performance, the overall system performance remained similar to that of the original system. Absorption refrigeration is promising as an up-and-coming alternative to a VCC system, but it is often hampered by excessive cooling unit sizes and a low COP.Funding for open access charge: CRUE-Universitat Jaume

Performance evaluation of modified compound organic Rankine-vapour compression cycle with two cooling levels, heating, and power generation

This work analyses a novel combined organic Rankine-compound ejector vapour compression cycle for power, cooling and heating production using a low-grade ground heat source as the primary heat source. Ultra-low global warming potential working fluids (R1234ze(E), R1243zf, and R1234yf) and parameters quantifying energy and exergy efficiency are considered. The system can be adapted to three operating modes, depending on the ground source temperature, ranging from 55 to 90 ◦C: power-cooling, power-heat pump heating, and powerground source heating. The results indicate that this system notably increases the overall performance of all investigated refrigerants. Compared to conventional organic Rankine and vapour compression cycles (ORC and VCC), the R1234ze(E) power-cooling mode shows the highest coefficient of performance (COP) increase, 18 %. Besides, including a recapture heat exchanger for condenser waste heat recovery can increase power generation by 58 %. At ground source temperatures up to 65 ℃, power generation and thermal efficiency increased in the power-heating mode due to the absence of the compressor power consumption. The exergy efficiency follows the ground source temperatures for all modes. In power-ground source heating mode, the exergy efficiency notably increased due to the absence of the heat pump exergy destruction.Funding for open access charge: CRUE-Universitat Jaume

Comprehensive experimental evaluation of R1234yf-based low GWP working fluids for refrigeration and heat pumps

This work presents an experimental comparison for low GWP refrigerants used in vapour compression cooling and heating systems. The study compares three lower global warming potential (GWP) refrigerants (R513A, R516A, and R1234yf) as drop-in refrigerants to replace the hydrofluorocarbon (HFC) R134a. Measurements are taken from a test rig at different steady-state conditions: for the cooling mode, the evaporating temperature is −5 °C, −10 °C and −15 °C, and is combined with two condensing temperatures (32.5 °C and 40 °C), and different internal heat exchanger (IHX) effectiveness. Besides, in the heating mode, the evaporating temperature is 7.5, 15 and 22.5 °C with five condensing temperatures (55 °C to 75 °C, step of 5 °C). In the cooling mode, R513A presented the highest system COP amongst the low GWP alternatives, increasing up to 8%. R516A shows the lowest system COP at the highest evaporation temperature; however, it exhibits the highest COP and capacity at the lowest evaporation temperature. The IHX positively influences the refrigerating effect for all adopted refrigerants. Regarding the heating mode, R513A presents the highest heating capacity with an average 3% increase, whereas R516A shows the lowest results. R513A shows comparable COP to R134a, especially at higher evaporating temperatures.Funding for open access charge: CRUE-Universitat Jaume

Experimental drop-in comparison of R516A and R134A for water-to-water refrigeration applications

R134a is still one of the most used hydrofluorocarbons (HFCs) in refrigeration and air conditioning applications. However, it should be phased out in the coming years because of its high global warming potential (GWP). The refrigeration sector needs to find as soon as possible technically suitable alternative refrigerants. R516A is a promising azeotropic mixture at medium-low temperatures. The operational and energetic performance of the lower GWP refrigerant R516A is analysed as a drop-in replacement to R134a. Experimental measurements are taken from in vapour compression test rig at several steady-state refrigeration conditions. The evaporating temperature is -5 ºC, -10 ºC and -15 ºC, and is combined with 32.5 ºC condensing temperature, considering the effect of the internal heat exchanger (IHX) effectiveness. R516A presents a good performance in terms of refrigerating effect and cooling capacity. R516A coefficient of performance (COP) is higher than R134a at the evaporating temperature of -15 ºC

Experimental evaluation of the azeotropic mixture R516A as an R134A drop-in alternative for moderately high-temperature heat pumps

The moderately high-temperature heat pump (MHTHP) is a market with a great potential to reduce greenhouse gas emissions from the heating sector. However, future proof MHTHPs cannot be based on hydrofluorocarbons with high global warming potential (GWP). Fourth-generation refrigerants with GWP below 150 are required. This work experimentally investigates the new azeotropic mixture R516A as a drop-in alternative to R134a, with a low GWP (142). Measurements are taken from a test rig at different steady-state operating conditions. The evaporating temperature is 7.5 ºC, 15 ºC and 22.5 ºC, and condensing temperature varies between 55 ºC and 75 ºC, at steps of 5 ºC. R516A presents a lower discharge temperature (average reduction of 7 ºC), which provides a safer operation for the compressor and increases its lifespan. R516A heating capacity reduction is 13.5% on average, with a reduced heating effect and comparable compressor power consumption. R516A shows a 12% COP reduction at higher evaporating temperatures

Conventional and Advanced Exergoeconomic Analysis of a Compound Ejector-Heat Pump for Simultaneous Cooling and Heating

[EN] This work focused on a compound PV/T waste heat driven ejector-heat pump system for simultaneous data centre cooling and waste heat recovery for district heating. The system uses PV/T waste heat as the generator's heat source, acting with the vapour generated in an evaporative condenser as the ejector drive force. Conventional and advanced exergy and advanced exergoeconomic analyses are used to determine the cause and avoidable degree of the components' exergy destruction rate and cost rates. Regarding the conventional exergy analysis for the whole system, the compressor represents the largest exergy destruction source of 26%. On the other hand, the generator shows the lowest sources (2%). The advanced exergy analysis indicates that 59.4% of the whole system thermodynamical inefficiencies can be avoided by further design optimisation. The compressor has the highest contribution to the destruction in the avoidable exergy destruction rate (21%), followed by the ejector (18%) and condenser (8%). Moreover, the advanced exergoeconomic results prove that 51% of the system costs are unavoidable. In system components cost comparison, the highest cost comes from the condenser, 30%. In the same context, the ejector has the lowest exergoeconomic factor, and it should be getting more attention to reduce the irreversibility by design improving. On the contrary, the evaporator has the highest exergoeconomic factor (94%).This research was funded by the Southern Technical University in Iraq, and Generalitat Valenciana (APOSTD/2020/032).Al-Sayyab, AKS.; Navarro-Esbrí, J.; Soto Francés, VM.; Mota-Babiloni, A. (2021). Conventional and Advanced Exergoeconomic Analysis of a Compound Ejector-Heat Pump for Simultaneous Cooling and Heating. Energies. 14(12):1-27. https://doi.org/10.3390/en14123511S127141

Physical activity phenotypes and mortality in older adults: a novel distributional data analysis of accelerometry in the NHANES

Physical activity is deemed critical to successful ageing. Despite evidence and progress, there is still a need to determine more precisely the direction, magnitude, intensity, and volume of physical activity that should be performed on a daily basis to effectively promote the health of individuals. This study aimed to assess the clinical validity of new physical activity phenotypes derived from a novel distributional functional analysis of accelerometer data in older adults. A random sample of participants aged between 65 and 80 years with valid accelerometer data from the National Health and Nutrition Examination Survey (NHANES) 2011–2014 was used. Five major clinical phenotypes were identified, which provided a greater sensitivity for predicting 5-year mortality and survival outcomes than age alone, and our results confirm the importance of moderate-to-vigorous physical activity. The new clinical physical activity phenotypes are a promising tool for improving patient prognosis and for directing to more targeted intervention planning, according to the principles of precision medicine. The use of distributional representations shows clear advantages over more traditional metrics to explore the effects of the full spectrum of the physical activity continuum on human healthOpen Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This research was funded by the Ministry of Science and Innovation of Spain, under Grant No. PID2021-123152OB-C21S

Detection of occludable angle with anterior segment optical coherence tomography and Pentacam as non-contact screening methods

Purpose To evaluate diagnostic capacity for occludable anterior chamber angle detection with anterior segment optical coherence tomography (AS-OCT) and Pentacam. Methods Observational cross-sectional study with AS-OCT and Pentacam. AS-OCT measures: angle opening distance from Schwalbe line (SL) perpendicular (AOD-SL-Perp) and vertical to iris (AOD-SL-Vert), and iridotrabecular angle (ITA). Pentacam measures: anterior chamber depth (ACD), anterior chamber volume (ACV), and anterior chamber angle (ACA). We analysed Spearman's correlation with gonioscopic classification. Area under receiver operating characteristic curves (AUCs) for occludable angle detection were compared. Agreement between iridocorneal values of methods was evaluated. Results Seventy-four left eyes of 74 patients. Correlation between temporal AS-OCT and gonioscopy: 0.83 (p < 0.0001) AOD-SL-Perp temporal, 0.82 (p < 0.0001) AOD-SL-Vert temporal, and 0.69 (p < 0.0001) ITA temporal. Correlation between AS-OCT nasal and gonioscopy: 0.74 (p < 0.0001) AOD-SL-Perp nasal, 0.74 (p < 0.0001) AOD-SL-Vert nasal, and 0.70 (p < 0.0001) ITA nasal. Correlation of Pentacam with temporal gonioscopy: 0.57 (p < 0.0001) ACD, 0.56 (p < 0.0001) ACV, and 0.63 (p < 0.0001) ACA. Correlation of Pentacam with nasal gonioscopy: 0.47 (IC 0.27-0.73, p < 0.0001) ACD, 0.49 (p < 0.0001) ACV, and 0.56 (CI 0.38-0.7, p < 0.0001) ACA. AS-OCT AUCs: AOD-SL-Perp temporal 0.89 (CI 0.80-0.95), AOD-SL-Vert 0.87 (CI 0.77-0.94), ITA temporal 0.88 (CI 0.78-0.94), AOD-SL-Perp nasal 0.83 (CI 0.72-0.91), AOD-SL-Vert nasal 0.87 (CI 0.77-0.94), and ITA nasal 0.91 (IC 0.81-0.96). Pentacam AUCs: ACD 0.76 (CI 0.64-0.85), ACV 0.75 (CI 0.63-0.84), and ACA 0.84 (CI 0.74-0.92). No statistical differences between different AUCs. Intraclass correlation coefficient (ICC) of ACA (Pentacam) with ITA temporal (AS-OCT) 0.59 and with nasal ITA nasal (AS-OCT) 0.65. Conclusion Both systems show high capacity for non-contact occludable angle detection. But agreement between methods is moderate or low

Molecular and Clinical Characteristics in 46 Families Affected with Peutz-Jeghers Syndrome

Germline mutations of the tumor suppressor gene LKB1/STK11 are responsible for the Peutz-Jeghers syndrome (PJS), an autosomal-dominant disorder characterized by mucocutaneous pigmentation, hamartomatous polyps, and an increased risk of associated malignancies. In this study, we assessed the presence of pathogenic mutations in the LKB1/STK11 gene in 46 unrelated PJS families, and also carried genotype-phenotype correlation in regard of the development of cancer in 170 PJS patients belonging to these families. All LKB1/STK11 variants detected with single-strand conformational polymorphism were confirmed by direct sequencing, and those without LKB1/STK11 mutation were further submitted to Southern blot analysis for detection of deletions/rearrangements. Statistical analysis for genotype-phenotype correlation was performed. In 59% (27/46) of unrelated PJS cases, pathogenic mutations in the LKB1/STK11 gene, including 9 novel mutations, were identified. The new mutations were 2 splice site deletion-insertions, 2 missenses, 1 nonsense, and 4 abnormal splice sites. Genotype-phenotype analysis did not yield any significant differences between patients carrying mutations in LKB1/STK11 versus those without mutations, even with respect to primary biliary adenocarcinoma. This study presents the molecular characterization and cancer occurrence of a large cohort of PJS patients, increases the mutational spectrum of LKB1/STK11 allelic variants worldwide, and provides a new insight useful for clinical diagnosis and genetic counseling of PJS familie

Evolution of Spherical Overdensity in Thawing Dark energy Models

We study the general evolution of spherical over-densities for thawing class of dark energy models. We model dark energy with scalar fields having canonical as well as non-canonical kinetic energy. For non-canonical case, we consider models where the kinetic energy is of the Born-Infeld Form. We study various potentials like linear, inverse-square, exponential as well as PNGB-type. We also consider the case when dark energy is homogeneous as well as the case when it is inhomogeneous and virializes together with matter. Our study shows that models with linear potential in particular with Born-Infeld type kinetic term can have significant deviation from the $\Lambda$CDM model in terms of density contrast at the time of virialization. Although our approach is a simplified one to study the nonlinear evolution of matter overdensities inside the cluster and is not applicable to actual physical situation, it gives some interesting insights into the nonlinear clustering of matter in the presence of thawing class of dark energy models.Comment: 11 pages, mnras style, 8 EPS figures, 1 table, improved version, Accepted for publication in MNRA