Design of PCM thermal storage unit for a HVAC system

L'objectiu del projecte és el disseny d'una unitat d'emmagatzematge d'energia térmica que optimitzi i millori l'eficiència del sistema de climatització. Aquesta unitat contindrà materials de canvi de fase (PCM) per emmagatzemar l'energia i estarà acoblada a un sistema de climatització format per una bomba de calor i una unitat de tractament de l'aire.

Compact thermal storage: a-state-of-the-art review of experimental results

Thermal energy storage (TES) can increase the thermal energy effieresa, of a process by reusing the waste heat from industrial process, solar energy or other sources. There are different ways to store thermal energy: by sensible heat, by latest heat, by sorption process or by chemical reaction. This thesrs provides a-state-of-the-art review of the experimental performance of TES systems based on solid gas sorption process and chemical reactions. The importance of theses processes is that provides a heat loss free storage system with a high energy density.

Analysis of thermal properties of phase change materials (PCM) using differential scanning calorimeter (DSC)

Commercially available PCM RT 20, RT 27, SP 22, A17 and SP 25 A8. Were analyzed using dynamic and step method of heat flux DSC. The results of the dinamic and step method were compared with commercial valures. It was found that RT 20 & RT 27 showed good conforming of results with commercial values while SP 22 A17 & SP 25 A8 did not show conformity.

Improvement of the thermal performance of commercial freezers using phase change materials (PCM)

The aim of this work is to improve the thermal performance of commercial freezers using phase change materials (PCM) and the prove the importance of the correct PCM selection (melting temperature) for each application. To do this a vertical freezer with and without macro encapsulation PCM are used to assess the benefits of using PCM in minimizing temperature fluctuations and to maintain at the lowest possible temperature the freezer under heat of losses.

Thermal energy storage with phase change materials in building envelopes

Els materials de canvi de fase (PCM) han estat considerats per a l’emmagatzematge tèrmic en edificis des de 1980. Amb la inclusió dels PCM en plaques de guix, guix, formigó o altres materials que s’utilitzen per a cobrir les parets, l’emmagatzematge tèrmic pot ser part de les estructures fins i tot en edificis lleugers. Les noves tècniques de microencapsulació han obert moltes possibilitats en aplicacions per a edificis. El treball que es presenta és el desenvolupament d’un formigó innovador mesclat amb PCM microencapsulat, amb un punt de fusió de 26 oC i una entalpia de canvi de fase de 110 kJ/kg. El primer experiment va ser la inclusió del PCM microencapsulat dins del formigó i la construcció d’una caseta amb aquest nou formigó-PCM. Es va construir una segona caseta al costat de la primera amb les mateixes característiques i orientació però amb formigó convencional que serveix com a referència. Durant els anys 2005 i 2006 es va analitzar el comportament d’ambdues casetes i més tard es va edificar un mur Trombe a la paret sud de totes dues per investigar la seva influència durant la tardor i l’hivern.

Poly(beta,L-malic acid)Doxorubicin ionic complex: A pH-dependent delivery system.

Poly(ß,L-malic acid) (PMLA) was made to interact with the cationic anticancer drug Doxorubicin (DOX) in aqueous solution to form ionic complexes with different compositions and an efficiency near to 100%. The PMLA/DOX complexes were characterized by spectroscopy, thermal analysis, and scanning electron microscopy. According to their composition, the PMLA/DOX complexes spontaneously self-assembled into spherical micro or nanoparticles with negative surface charge. Hydrolytic degradation of PMLA/DOX complexes took place by cleavage of the main chain ester bond and simultaneous release of the drug. In vitro drug release studies revealed that DOX delivery from the complexes was favored by acidic pH and high ionic strength

Comblike poly(a-alkyl g glutamate)s: computer simulation studies of an intermediate thermal phase.

Monte Carlo (MC) simulations have been used to study the structure of an intermediate thermal phase of poly(R-octadecyl ç,D-glutamate). This is a comblike poly(ç-peptide) able to adopt a biphasic structure that has been described as a layered arrangement of backbone helical rods immersed in a paraffinic pool of polymethylene side chains. Simulations were performed at two different temperatures (348 and 363 K), both of them above the melting point of the paraffinic phase, using the configurational bias MC algorithm. Results indicate that layers are constituted by a side-by-side packing of 17/5 helices. The organization of the interlayer paraffinic region is described in atomistic terms by examining the torsional angles and the end-to-end distances for the octadecyl side chains. Comparison with previously reported comblike poly(â-peptide)s revealed significant differences in the organization of the alkyl side chains.

Relaxation and derelaxation of pure and hydrogenated amorphous silicon during thermal annealing experiments

The structural relaxation of pure amorphous silicon a-Si and hydrogenated amorphous silicon a-Si:H materials, that occurs during thermal annealing experiments, has been analyzed by Raman spectroscopy and differential scanning calorimetry. Unlike a-Si, the heat evolved from a-Si:H cannot be explained by relaxation of the Si-Si network strain but it reveals a derelaxation of the bond angle strain. Since the state of relaxation after annealing is very similar for pure and hydrogenated materials, our results give strong experimental support to the predicted configurational gap between a-Si and crystalline silicon.

Histologic evaluation of thermal damage produced on soft tissues by CO2, Er,Cr:YSGG and diode lasers

Objective: The aim of this in vitro experimental study was to perform histological evaluation of the thermal effect produced on soft tissue irradiated with CO2, Er,Cr:YSGG or diode lasers. Study design: Porcine oral mucosa samples were irradiated with Er,Cr:YSGG laser at 1 W with and without water / air spray, at 2 W with and without water / air spray, and at 4 W with water / air spray, with CO2 laser at 1 W, 2 W, 10 W, 20 W continuous mode and 20 W pulsed mode and diode laser at 2W, 5W, and 10W pulsed mode. The thermal effect was evaluated measuring the width of damaged tissue adjacent to the incision, stained positively for hyalinized tissue with Hematoxylin-Eosin and Masson Trichrome stains. Besides, histological changes in the irradiated tissue were described using subjective grading scales. Results: The evaluated lasers developed a wide range of thermal damage with significant differences between groups. The samples with lowest thermal effect were those irradiated with Er,Cr:YSGG laser using water / air spray, followed by CO2 and diode lasers. Conclusions: Emission parameters of each laser system may influence the thermal damage inflicted on the soft tissue, however, the wave length of each laser determines the absorption rate characteristics of every tissue and the thermal effect

Studying the non-thermal lobes of IRAS 16547-4247 through a multi-wavelength approach

In recent years, massive protostars have turned out to be a possible population of high-energy emitters. Among the best candidates is IRAS 16547-4247, a protostar that presents a powerful outflow with clear signatures of interaction with its environment. This source has been revealed to be a potential high-energy source because it displays non-thermal radio emission of synchrotron origin, which is evidence of relativistic particles. To improve our understanding of IRAS 16547-4247 as a high-energy source, we analyzed XMM-Newton archival data and found that IRAS 16547-4247 is a hard X-ray source. We discuss these results in the context of a refined one-zone model and previous radio observations. From our study we find that it may be difficult to explain the X-ray emission as non-thermal radiation coming from the interaction region, but it might be produced by thermal Bremsstrahlung (plus photo-electric absorption) by a fast shock at the jet end. In the high-energy range, the source might be detectable by the present generation of Cherenkov telescopes, and may eventually be detected by Fermi in the GeV range.

Assessment of the levels of degradation in fat co- and by-products for feed uses and their relationships with some lipid composition parameters

This paper discusses the levels of degradation of some co- and byproducts of the food chain intended for feed uses. As the first part of a research project, 'Feeding Fats Safety', financed by the sixth Framework Programme-EC, a total of 123 samples were collected from 10 European countries, corresponding to fat co- and byproducts such as animal fats, fish oils, acid oils from refining, recycled cooking oils, and other. Several composition and degradation parameters (moisture, acid value, diacylglycerols and monoacylglycerols, peroxides, secondary oxidation products, polymers of triacylglycerols, fatty acid composition, tocopherols, and tocotrienols) were evaluated. These findings led to the conclusion that some fat by- and coproducts, such as fish oils, lecithins, and acid oils, show poor, nonstandardized quality and that production processes need to be greatly improved. Conclusions are also put forward about the applicability and utility of each analytical parameter for characterization and quality control.

Response of the Thermal Conductivity as a Function of Water Content of a Burnt Mediterranean Loam Soil

The purpose of this research is to explore the variability on the soil thermal conductivity -λ- after a prescribe fire, and to assess the effects of the ashes on the heat transfer once it"s were incorporated into the soil matrix. Sampling plot was located in the Montgrí Massif (NE of Spain). A set of 42 soil samples between surface and 5 cm depth was collected before and after the fire. To characterize the soil chemical and physical variables were analyzed. To determine the vari-ability on the soil λ a dry-out curve per scenario (before and after fire) was determined. SoilRho® method based on ASTM D-5334-08 which was validated by LabFerrer was used. Soil thermal conductivity has shown changes in their values. Indeed, in all moisture scenarios the values of soil λ decreased after soil was burnt. The critical point in the rela-tionship ϴ (λ) for the soil after fire which always was stronger than soil before to be burnt. Soil with"white" ashes showed a high thermal conductivity. An X-Ray diffractometry analysis allowed to clarify and to verify these results. To sum up, we could say that thermal conductivity presents changes when the scenario changes, i.e. before and after to be burnt. On the other hand, the volume of ashes incorporated on the soil increased the differences between no burnt and burnt soil, showing even some improvements on the heat transfer when water content started to govern the process.

Thermal increment due to ErCr: YSGG and CO2 laser irradiation of different implant surfaces. A pilot study

Objective: An evaluation and comparison is made of the thermal increment at different implant surfaces during irradiation with CO2 and ErCr:YSGG lasers. Study design: Five threaded and impacted implants with four types of surfaces were inserted in an adult pig rib: two implants with a hydroxyapatite surface (HA)(impacted and threaded, respectively), a machined titanium surface implant (TI mach), a titanium plasma spray surface implant (TPS), and a sandblasted, acid-etched surface implant (SBAE). A 0.5-mm diameter bone defect was made in the implant apical zone, and a type-K thermocouple (Termopar)® was placed in contact with the implant. The implants were irradiated in the coronal zone of each implant with a CO2 (4 W continuous mode) and an ErCr:YSGG laser (1.5 W, pulsed mode) first without and then with refrigeration. The temperature variations at the implant apical surface were recorded. Results: An apical temperature increase was recorded in all cases during CO2 and ErCr:YSGG laser irradiation without refrigeration. However, when the ErCr:YSGG was used with a water spray, a decrease in temperature was observed in all implants. The acid-etched and sandblasted surfaces were those most affected by the thermal changes. Conclusions: The ErCr:YSGG laser with a water spray applied to the sealing cap or coronal zone of the implants does not generate thermal increments in the apical surface capable of adversely affecting osseointegration and the integrity of the peri-implant bone tissue

Identification of metabolites and thermal transformation products of quinolones in raw cow milk by liquid chromatography coupled to high resolution mass spectrometry

The presence of residues of antibiotics, metabolites, and thermal transformation products (TPs), produced during thermal treatment to eliminate pathogenic microorganisms in milk, could represent a risk for people. Cow"s milk samples spiked with enrofloxacin (ENR), ciprofloxacin (CIP), difloxacin (DIF), and sarafloxacin (SAR) and milk samples from cows medicated with ENR were submitted to several thermal treatments. The milk samples were analyzed by liquid chromatography-mass spectrometry (LC-MS) to find and identify TPs and metabolites. In this work, 27 TPs of 4 quinolones and 24 metabolites of ENR were found. Some of these compounds had been reported previously, but others were characterized for the first time, including lactose-conjugated CIP, the formamidation reaction for CIP and SAR, and hydroxylation or ketone formation to produce three different isomers for all quinolones studied.

Identification of metabolites and thermal transformation products of quinolones in raw cow milk by liquid chromatography coupled to high resolution mass spectrometry.

The presence of residues of antibiotics, metabolites, and thermal transformation products (TPs), produced during thermal treatment to eliminate pathogenic microorganisms in milk, could represent a risk for people. Cow"s milk samples spiked with enrofloxacin (ENR), ciprofloxacin (CIP), difloxacin (DIF), and sarafloxacin (SAR) and milk samples from cows medicated with ENR were submitted to several thermal treatments. The milk samples were analyzed by liquid chromatography-mass spectrometry (LC-MS) to find and identify TPs and metabolites. In this work, 27 TPs of 4 quinolones and 24 metabolites of ENR were found. Some of these compounds had been reported previously, but others were characterized for the first time, including lactose-conjugated CIP, the formamidation reaction for CIP and SAR, and hydroxylation or ketone formation to produce three different isomers for all quinolones studied.