Thermal Metrics for Data Centers: A Critical Review

Thermal management and air distribution performance are assuming a key role for achieving the energy saving and the IT equipment reliability for data centers (DCs). In recent years, to monitor and to control their variation several thermal performance metrics were introduced. This work presents a critical review on the most important thermal indices for DCs currently used. The main formulas and physical models on which they are based were discussed. Moreover, a critical analysis on the main advantages and drawbacks of each metric is carried out

Physico-chemical and sensory characterization of a fruit beer obtained with the addition of cv. Lambrusco grapes must

In 2015, Italian Grape Ale (IGA) beers have been included as a new provisional sub-category of special-type fruit beers by the Beer Judge Certification Program, including those products whose brewing process is carried out in presence of determined quantities of grape must. However, information on the effects of these additions on the composition of final beers are still scarce. This work is hence focused on the chromatic, volatile, phenolic and sensory characterization of IGA beers obtained with the addition of grape musts during brewing process. To this aim, different amounts of must (5, 10 and 20%) from cv. Lambrusco red grapes were added to a lager wort before primary fermentation. Beers were then characterized by HPLC-MS, GC-MS and sensory analysis in order to determine phenolic and aroma compounds along with their sensory attributes. Results confirmed the addition of must from cv. Lambrusco grapes capable to enrich beers in color, acids, phenolic (up to 7-folded increased) and volatile compounds, while giving complexity to beers. These results, which were confirmed by a trained sensory panel, are among the very first insights on the impact of red grape must in brewing, both from a compositional and sensory point of view

Performance characteristics of a hybrid solar receiver combustor utilising hydrogen or syngas

The use of hybrid solar thermal devices, which harness the energy from both concentrated solar radiation and combustion, is receiving growing attention due to their potential to provide a firm and dispatchable thermal energy supply while lowering the costs of energy systems and assisting the penetration of renewable energy. The Hybrid Solar Receiver Combustor (HSRC), which directly integrates the function of a solar receiver and a combustor into a single device, is a particularly promising hybrid technology. Its design allows the receiver to operate in three modes: solar-only, combustion-only and a mixed-mode (a combination of both solar and combustion). Compared with the present state-of-the-art in hybrid solar-combustion systems (which collect the thermal energy from the solar and combustion sources in separate devices and then combine them subsequently), the HSRC offers a reduction in total infrastructure (and hence capital costs), heat-exchange surface area, start-up/shut-down losses and pollutant emissions, due to a reduced need to start-up the back-up combustion plant. Also, the use of the HSRC with renewable fuels (e.g. hydrogen, syngas) offers the additional potential for low-cost carbon neutral or carbon-negative energy, although no data on performance for systems fed with alternative fuels are presently available. To this aim, the present work provides the first direct measurement of the performance of a Hybrid Solar Receiver Combustor (HSRC) fed with hydrogen-based fuels. A laboratory-scale HSRC prototype operated in the Moderate or Intense Low oxygen Dilution (MILD) combustion regime was tested at a nominal capacity of 12-kWth for both the combustion-only and mixed mode, using hydrogen and syngas (H2/CO=2/1 v/v) as fuels. A 5-kWel xenon-arc lamp was used to simulate solar radiation into the device. The influence of the mode of operation on the thermal efficiency, heat losses, heat flux distribution within the cavity and pollutant emissions are reported for a range of values of the heat extraction. It was found that the combustion process can be successfully stabilised within the HSRC over a wide range of operating conditions, and in the mixed-mode of operation, providing ultra-low NOx emissions. The thermal performance was found to be similar for all the modes of operation, despite the different nature of the two energy sources and fuel composition. Overall, this study highlights that, if renewable H2 or syngas are used as fuels, the device can efficiently operate in all the modes of operation employing 100% renewable energy.Alfonso Chinnici, Graham J. Nathan, and Bassam B. Dall

Novelty of Italian Grape Ale (IGA) beer: Influence of the addition of Gamay macerated grape must or dehydrated Aleatico grape pomace on the aromatic profile

: A new category of fruit style beer resulting from the addition of grape matrices is named Italian Grape Ale (IGA). In this paper, we report data on an experimental work to produce IGA beers, adding macerated (CO2 or N2) red Gamay grape must or Aleatico grape pomace resulting from a grape dehydration process. Our hypothesis, that these wine processes can produce volatile organic compounds (VOCs) to characterize these IGA beers which was confirmed by chemical, sensory and aromatic results. IGA beers especially the one with gas-macerated grape musts (IGA-C and IGA-N) showed higher alcohol content than ALE beer (Control) and a higher polyphenol content and antioxidant activity. As regards VOCS, IGA beers increased the concentration of some classes (i.e., alcohols, esters, norisoprenoids) and IGA-N was better characterized by specific compounds such as isobutyric acid, phenylacetate, tyrosol, ethyl hydrogen succinate. Finally, E-nose and sensory evaluation discriminated significantly all the IGA beers

Efficacy of biodegradable, antimicrobial packaging on safety and quality parameters maintenance of a pear juice and rice milk-based smoothie product

In this study, the effect of a Polylactic acid (PLA) antimicrobial biodegradable packaging activated with lysozyme by cold plasma on a pear juice and rice milk-based smoothie was investigated. The antimicrobial effect of the active innovative packaging was evaluated In-vitro and on the smoothie inoculated with Listeria monocytogenens and Lactobacillus plantarum. After a preliminary evaluation of the lysozyme release kinetics in different conditions, its influence on some smoothie quality parameters (water activity, pH, colour and microbial growth) was evaluated. In-vitro trials showed an antimicrobial activity of the activated film against different microorganisms. Inoculated smoothies packed in activated and not materials were stored at 10 and 4 °C and analysed overtime. Results showed the capability of the activated package to inhibit Listeria monocytogenes and to maintain a better and a more stable colour compared to control ones. Activated pouches showed the best antimicrobial effect on samples stored at 10 °C compared to 4 °C, difference due to the faster lysozyme release kinetic from the packaging material at the highest storage temperature. Obtained results highlight the potentiality of the biodegradable packaging activated with lysozyme to be applied successfully in food industry, to improve safety and extend shelf-life of juice-based product

Physico-chemical and sensory characterization of a fruit beer obtained with the addition of cv. Lambrusco grapes must

In 2015, Italian Grape Ale (IGA) beers have been included as a new provisional sub-category of special-type fruit beers by the Beer Judge Certification Program, including those products whose brewing process is carried out in presence of determined quantities of grape must. However, information on the effects of these additions on the composition of final beers are still scarce. This work is hence focused on the chromatic, volatile, phenolic and sensory characterization of IGA beers obtained with the addition of grape musts during brewing process. To this aim, different amounts of must (5, 10 and 20%) from cv. Lambrusco red grapes were added to a lager wort before primary fermentation. Beers were then characterized by HPLC-MS, GC-MS and sensory analysis in order to determine phenolic and aroma compounds along with their sensory attributes. Results confirmed the addition of must from cv. Lambrusco grapes capable to enrich beers in color, acids, phenolic (up to 7-folded increased) and volatile compounds, while giving complexity to beers. These results, which were confirmed by a trained sensory panel, are among the very first insights on the impact of red grape must in brewing, both from a compositional and sensory point of view