Thermal Performance Analysis of Triple Heat Exchangers via the Application of an Innovative Simplified Methodology

Despite the double tube heat exchangers, in the triple tube heat exchangers, there are three fluids, and the methodology based on the assessment of the logarithmic mean temperature difference is no longer applicable. Moreover, in triple tube heat exchangers, there are two overall heat transfer coefficients dependent on each other. As such, it is necessary to solve them simultaneously, thus making the evaluation of the thermal performance of triple tube heat exchangers more complex compared to double tube heat exchangers. Among the proposed approaches in the literature to solve this issue, one of the most powerful and commonly adopted in several engineering applications is the parameter estimation procedure. Nevertheless, for the specific implementation examined in our analysis, a thorough numerical model of the triple tube heat exchanger was required to apply the inverse procedure properly. Furthermore, it is mandatory to measure the temperature of the three fluids at the inlet and outlet sections. In so doing, the inverse procedure can be successfully applied to the characterisation of triple tube heat exchangers tested in well-equipped research labs; however, its application to heat transfer devices operating in industrial facilities can be difficult. In order to overcome this limitation, an innovative parameter estimation technique that enables the evaluation of the thermal performance of this type of heat transfer devices is presented. The suggested methodology is based on a simple model of the triple tube heat exchanger in which an equivalent double tube heat exchanger is considered, thus requiring only four temperature measurements. The results obtained by applying this simplified methodology are numerically validated and compared to those obtained using a comprehensive mode

Thermal characterisation of Triple Concentric Tube Heat Exchangers by applying parameter estimation: Direct problem implementation

Heat transfer enhancement in heat exchangers's design represents a key technological challenge because of the increase in the cost of energy and raw materials. A promising technology is represented by the triple tube heat exchangers, in which the heat transfer is enhanced in comparison with the traditional double tube heat exchangers, due to the larger heat transfer area per unit length. Among the different methodologies that can be adopted to assess the performance of the triple tube heat exchangers, parameter estimation procedure represents a promising tool, since it has been successfully applied in many disciplines of engineering. To apply this inverse technique, it is mandatory defining the direct problem, which for the issue here addressed allows evaluating the outlet temperatures of the fluids flowing in the heat exchanger. Since in a triple tube heat exchanger there are three fluids, the approach based on the evaluation of the logarithmic mean temperature difference is no longer valid and an alternative procedure has to be followed. In the present analysis a numerical model for the performance evaluation of triple tube heat exchangers is presented. The validation of the proposed numerical model, carried out by adopting the analytical model available in literature, highlights that the model can be considered accurate and reliable. Moreover, the computational time required to solve the set of equations is very limited

Improved Care for Teens in Trouble With Drugs, Alcohol, and Crime

Outlines how drug treatment providers developed RWJF's Reclaiming Futures model for collaborating with others and integrating evidence-based practices to sustain improvement in the juvenile justice system's treatment programs. Includes recommendations

Design and implementation of a modulating test plant to assess the performance of innovative cross-flow heat recovery units for air conditioning system: Preliminary results

Nowadays global warming has increased consciousness of the dangers of energy wastefulness: in the last 50 years the temperature of the Earth's surface rose by approximately 1 °C. The building sector is responsible for a very high percentage of world carbon emissions and with the increasing of the request for comfort, heating, ventilation and air conditioning, buildings energy consumption is rapidly growing. Consequently, it appears fundamental the role played by the improvement of buildings energy performance within global policies of emissions reduction. In this context an increasing attention is given to the energy waste reduction in tertiary sector: bars, offices, restaurants, meetings, shops, school buildings, gyms and in general in the buildings in which the minimization of the energy dissipation is requested. The present study is part of the NANOFANCOIL project (POR-FESR 2014-2020): one of the objectives was the design and implementation of a modulating test plant to assess the performance of innovative cross-flow heat recovery units for air conditioning system. This experimental setup was mainly composed by two climatic chambers that enabled to simulate the environmental conditions of interest. The temperature could vary from -20°C to 0°C and from 10°C to 30°C for the cold and the hot chamber, respectively (i.e. the outdoor and the indoor environment). Moreover, the climatic chamber that simulates the indoor environment could be controlled also in terms of humidity thanks to a steam humidifier that guaranteed 5 kg/h of vapour. Preliminary results about the heat transfer behaviour of a cross-flow heat recovery unit (air-to-air) for controlled mechanical ventilation systems that employs mini-channels in order to increase performance and reduce size and costs are presented here

Impact of indirect and ohmic heating sterilization processes on quality parameters of apple puree: Application in a real industrial line

The aim of the present work is to investigate the impact of the production process and heat treatment technology to produce sterilized apple puree in the case of a real industrial production line. The technologies considered for the sterilisation process are traditional indirect thermal heating and ohmic heating, while the results will be expressed in terms of residual amount of vitamin C, Furfural content and finally HunterLab colour space (L, a, b value). The samples for the evaluation of the comparison parameters have been taken in 3 different steps of the production process, i.e. in the fresh product, after hot finisher (after extraction) and at the end of the line (after sterilization and bottling). It has been observed that both processes considered showed similar performance for all the various parameters evaluated, leading to a very similar final product. This result is somehow unexpected since the Ohmic technology has demonstrated in the last years to bring significant advantages in terms of preserving of nutrients and of colour stability. This could be since apple puree is a sort of homogeneous product, while the best advantages for the Ohmic heating are expected to be found in heterogeneous products containing pieces or particulate matter. But the main reason is related to the fact that in the present work the focus is on the whole process and not only on the heat treatment technology. One of the aims is to put the attention on the importance of specifically designing the whole production line: the adoption of ohmic heating or other innovative technologies to shield nutrients and colour will be wasted if the rest of the production line is not specifically designed to obtain such objectives

Genome Sequence of the Lager Brewing Yeast, an Interspecies Hybrid

This work presents the genome sequencing of the lager brewing yeast (Saccharomyces pastorianus) Weihenstephan 34/70, a strain widely used in lager beer brewing. The 25 Mb genome comprises two nuclear sub-genomes originating from Saccharomyces cerevisiae and Saccharomyces bayanus and one circular mitochondrial genome originating from S. bayanus. Thirty-six different types of chromosomes were found including eight chromosomes with translocations between the two sub-genomes, whose breakpoints are within the orthologous open reading frames. Several gene loci responsible for typical lager brewing yeast characteristics such as maltotriose uptake and sulfite production have been increased in number by chromosomal rearrangements. Despite an overall high degree of conservation of the synteny with S. cerevisiae and S. bayanus, the syntenies were not well conserved in the sub-telomeric regions that contain lager brewing yeast characteristic and specific genes. Deletion of larger chromosomal regions, a massive unilateral decrease of the ribosomal DNA cluster and bilateral truncations of over 60 genes reflect a post-hybridization evolution process. Truncations and deletions of less efficient maltose and maltotriose uptake genes may indicate the result of adaptation to brewing. The genome sequence of this interspecies hybrid yeast provides a new tool for better understanding of lager brewing yeast behavior in industrial beer production

On the complexity of the Saccharomyces bayanus taxon: hybridization and potential hybrid speciation

Although the genus Saccharomyces has been thoroughly studied, some species in the genus has not yet been accurately resolved; an example is S. bayanus, a taxon that includes genetically diverse lineages of pure and hybrid strains. This diversity makes the assignation and classification of strains belonging to this species unclear and controversial. They have been subdivided by some authors into two varieties (bayanus and uvarum), which have been raised to the species level by others. In this work, we evaluate the complexity of 46 different strains included in the S. bayanus taxon by means of PCR-RFLP analysis and by sequencing of 34 gene regions and one mitochondrial gene. Using the sequence data, and based on the S. bayanus var. bayanus reference strain NBRC 1948, a hypothetical pure S. bayanus was reconstructed for these genes that showed alleles with similarity values lower than 97% with the S. bayanus var. uvarum strain CBS 7001, and of 99¿100% with the non S. cerevisiae portion in S. pastorianus Weihenstephan 34/70 and with the new species S. eubayanus. Among the S. bayanus strains under study, different levels of homozygosity, hybridization and introgression were found; however, no pure S. bayanus var. bayanus strain was identified. These S. bayanus hybrids can be classified into two types: homozygous (type I) and heterozygous hybrids (type II), indicating that they have been originated by different hybridization processes. Therefore, a putative evolutionary scenario involving two different hybridization events between a S. bayanus var. uvarum and unknown European S. eubayanus-like strains can be postulated to explain the genomic diversity observed in our S. bayanus var. bayanus strains

The Minimum Detectable Damage as an Optimization Criterion for Performance-based Sensor Placement

International audienc

Analysis of Microplastics in Food Samples

This chapter presents a compilation of the analytical techniques used to detect and analyze microplastics in food. A detailed description of microplastics found in different samples is provided as well as an estimate of the annual intake of these particles. A total of 22–37 milligrams of microplastics per year was found. The factors that can influence the presence of particles in food, especially table salt, are discussed, showing that a background presence of microplastics in the environment can explain a large amount of experimental data.Support for this work was provided by the CTQ2016-76608-R project from the Ministry of Economy, Industry and Competitiveness (Spain) and by the University of Alicante under the project UAUSTI18-06

Evidence for Divergent Evolution of Growth Temperature Preference in Sympatric Saccharomyces Species

The genus Saccharomyces currently includes eight species in addition to the model yeast Saccharomyces cerevisiae, most of which can be consistently isolated from tree bark and soil. We recently found sympatric pairs of Saccharomyces species, composed of one cryotolerant and one thermotolerant species in oak bark samples of various geographic origins. In order to contribute to explain the occurrence in sympatry of Saccharomyces species, we screened Saccharomyces genomic data for protein divergence that might be correlated to distinct growth temperature preferences of the species, using the dN/dS ratio as a measure of protein evolution rates and pair-wise species comparisons. In addition to proteins previously implicated in growth at suboptimal temperatures, we found that glycolytic enzymes were among the proteins exhibiting higher than expected divergence when one cryotolerant and one thermotolerant species are compared. By measuring glycolytic fluxes and glycolytic enzymatic activities in different species and at different temperatures, we subsequently show that the unusual divergence of glycolytic genes may be related to divergent evolution of the glycolytic pathway aligning its performance to the growth temperature profiles of the different species. In general, our results support the view that growth temperature preference is a trait that may have undergone divergent selection in the course of ecological speciation in Saccharomyces