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.

Use of a pre-sidedress soil nitrate test (PSNT) to determine nitrogen fertilizer requirements for irrigated corn

In the present study, a 2-year N rate response experiment was conducted in different fields to monitor NO3-N soil profiles, N accumulation by the crop and final crop performance, in order to assess if soil NO3-N at pre-sidedressing (Pre-Sidedress Soil Nitrate Test, PSNT) is a reliable indicator for soil N availability for corn in the irrigated area served by canal d’Urgell (Lleida, Spain), and if the test can be used to separate responsive fields from non-responsive fields to sidedress N fertilizer applications. Preliminary soil N availability (N sidedress fertilizer rate + PSNT) critical levels to identify fields that need supplementary N fertilizer applications were established at ca. 300 and 210 kg NO3-N·ha–1, for PSNTrooting–zone and PSNT0–30 cm, respectively (for a yield goal of 14 t grain·ha–1).

Courtship and mating behaviour of the Mediterranean corn borer, Sesamia nonagrioides (Lepidoptera: Noctuidae)

Se describe la secuencia de cortejo y apareamiento de machos y hembras de Sesamia nonagrioides (Lefèbvre) en el laboratorio. Esta secuencia no varió en presencia o ausencia de plantas de maíz. Se estudió la capacidad de atracción de un sexo sobre el otro atando el individuo de un sexo y dejando libre al complementario. La secuencia de cortejo y apareo de las hembras atadas fue la misma que la de las no atadas, pero los machos atados permanecieron absolutamente inactivos. La edad de los adultos (1 día versus 2 días) no afectó al porcentaje de apareamiento. Se encontraron diferencias en la hora del inicio de la llamada de las hembras y en la edad de las hembras en la primera llamada entre la población estudiada y lo descrito para una población griega, diferencias que podrían estar relacionadas con el origen geográfico. Se discute el papel de los penachos abdominales de los machos en el vuelo de cortejo, rechazándose que estimulen el comportamiento de llamada de las hembras o que las atraigan. Cuando no se aplicaron feromonas, el porcentaje de apareamiento en el laboratorio o en el campo no varió cuando aumentó la densidad de la población. Sin embargo, en los campos en que se aplicó confusión sexual, el porcentaje de apareamiento aumentó al aumentar la densidad de adultos. En la discusión se aportan algunas consecuencias para la investigación de la composición de las feromonas y su uso para el seguimiento de plagas y el control mediante confusión sexual.

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.

Nitrogen replacement value of alfalfa to corn and wheat under irrigated Mediterranean conditions

In crop rotations that include alfalfa (Medicago sativa L.), agronomic and environmental concerns mean that it is important to determine the N fertilizer contribution of this legume for subsequent crops in order to help to increase the sustainability of cropping systems. To determine the N fertilizer replacement value (FRV) of a 2-yr alfalfa crop on subsequent crops of corn (Zea mays L.) followed by wheat (Triticum aestivum L.) under irrigated Mediterranean conditions, two 4-yr rotations (alfalfa-corn-wheat and corn-corn-corn-wheat) were conducted from 2001 to 2004 in a Typic Xerofluvent soil. Corn yields were compared after two years of alfalfa and a third year of corn under monoculture and wheat yields were also compared after both rotations. Corn production after alfalfa outyielded monoculture corn at all four rates of N fertilizer application analyzed (0, 100, 200 and 300 kg N/ha). The FRV of 2-yr alfalfa for corn was about 160 kg N/ha. Wheat grown after the alfalfa-corn rotation outyielded that grown after corn under monoculture at both the rates of N studied (0 and 100 kg N/ha). The FRV of alfalfa for wheat following alfalfa-corn was about 76 kg N/ha. Soil NO3 -N content after alfalfa was greater than with the corn monoculture at all rates of N fertilizer application and this higher value persisted during the second crop after alfalfa. This was probably one of the reasons for the better yields associated with the alfalfa rotation. These results make a valuable contribution to irrigated agriculture under mediterranean conditions, show reasons for interest in rotating alfalfa with corn, and explain how it is possible to make savings when applying N fertilizer.

Short communication. Mutual pheromone antagonism in two sympatric corn borers, Sesamia nonagrioides and Ostrinia nubilalis, under field conditions

In previous studies, we demonstrated cross-antagonism in pheromone perception between pheromone componentsof the two corn (Zea mays L.) borers Sesamia nonagrioides Lefèbvre (Lepidoptera: Noctuidae) and Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) in the laboratory and in the field. The two pheromone components identified as responsible for this cross-antagonism were Z 11-16:Ald, a minor component of S. nonagrioides pheromone, and Z 11-14:Ac, the main component of the pheromone of the Z-strain of O. nubilalis, which inhibited the response of O. nubilalis and S. nonagrioides, respectively. Here, we study this antagonism phenomenon in the field by air permeation of maize plots with each of the two components separately and measurement of mating in caged couples of the two corn borers on treated and untreated plots during three years. A significant reduction in mating rates was observed on the permeated plots: 7% for S. nonagrioides and 12% for O. nubilalis. When dispenser charges (200 ng) were increased by 50% and 75% in the third year, no decrease in mating rates was recorded at either of the increased concentrations. On the other hand, the use of large cages resulted in an increase of 8% to 12% in the percentage of unmated females in each of the two corn borers suggesting that at more realistic field corn borer densities, 0,1 couples/plant instead of the 2 couples/plant used in this experiment, cross-antagonism in the two corn borers could be higher than that recorded in small cages.

Effect of prestorage curing on storage life, internal and external qualities of sweet orange (Citrus sinensis)

Orange fruits from two seasons, in April and August 2006 representing late 2005 and early 2006 harvests respectively were cured in hot air at 36-37(0)C to 1%, 3%, 5% and 7% weight loss before storage at 28(0)C and 86% relative humidity (RH). The fruits were observed for incidence of decay, further weight loss, juice content, firmness or softening of the peel, total soluble solids (TSS), pH, titratable acidity, and colour during storage. Curing reduced the incidence of decay. All control fruits were rotten by day 21 in August harvest while 22.5% of the control was rotten by day 56 in the April harvest. Storage life was extended beyond 56 days in fruits cured with 1, 3, 5 and 7% in April harvest as there was no decay throughout, while decay incidence in August harvest was 88.9, 61.1, 22.2 and 31.3% in 1, 3, 5 and 7% respectively. Penicillium digitatum, Phytophthora sp., Alternaria citri and Collectotrichum gloeosporioides were among decay causing moulds detected. Control fruits lost more weight during storage than cured fruits did. Fruit rind hardening was more noticed in the control and those cured to 1% weight loss, especially from the April harvest. It was insignificant in other treatments in both trials. Titratable acidity, pH, juice content and TSS were not affected by the treatment. Colour change to yellow was however retarded by curing. Curing to 5% weight loss was best for decay control and quality retention.

Modified atmosphere packaging extending the storage life of 'douradão' peach

'Douradão' peach is a perishable product and when cold stored is subject to chilling injury. The objective of the experiment was to evaluate the effect of modified atmosphere packaging (MAP) and cold storage on quality and storage life of these peaches. Fruits were packed in polypropylene (PP) trays and placed inside low density polyethylene (LDPE) bags (30, 50, 60, 75 μm thickness) with active modified atmosphere (10 kPa CO2 + 1.5kPa O2, balance N2). The control was made with peaches held in nonwrapped PP trays. Fruits were kept at 1 ± 1 °C and 90 ± 5% relative humidity (RH) for 28 days and CO2 and O2 within packages was monitored every two days. After 14, 21 and 28 days, samples were withdrawn from MAP and kept in air at 25 ± 1 °C and 90 ± 5% RH for ripening. On the day of removal from the cold storage and after 4 days, peaches were evaluated for weight loss, decay incidence, flesh firmness, woolliness incidence, soluble solids content (SSC), titratable acidity (TA) and juice content. The results showed that MAP had influence on reducing weight loss and prevented postharvest decay. MAP of 1-2 kPa O2 and 3-6 kPa CO2 at 1 °C (from 50 and 60 μm LDPE films) were effective for keeping good quality of 'Douradão' peaches during 28 days of storage, the ripe fruits showed reduced incidence of woolliness, adequate juiciness and flesh firmness. Packages of 30 and 75 μm LDPE films were ineffective for reducing woolliness during cold storage. MAP fruits showed lower SSC and no relevant effect on TA. Control fruits did not present marketable conditions after 14 days of cold storage.

Subsurface drip irrigation emitter spacing effects on soil water redistribution, corn yield and water productivity

Emitter spacings of 0.3 to 0.6 m are commonly used for subsurface drip irrigation (SDI) of corn on the deep, silt loam soils of the U.S. Great Plains. Subsurface drip irrigation emitter spacings of 0.3, 0.6, 0.9 and 1.2 m were examined for the resulting differences in soil water redistribution, corn grain yield, yield components, seasonal water use, and water productivity in a 4‐year field study (2005 through 2008) at the Kansas State University Northwest Research‐Extension Center, Colby, Kansas. The results indicate that there is increased preferential water movement along the dripline (parallel) as compared to perpendicular to the dripline and that this phenomenon partially compensates for wider emitter spacings in terms of soil water redistribution. Corn yield and water productivity (WP) were not significantly affected by the emitter spacing with application of a full irrigation regime

Exercise performed immediately after fructose ingestion enhances fructose oxidation and suppresses fructose storage.

BACKGROUND: Exercise prevents the adverse effects of a high-fructose diet through mechanisms that remain unknown. OBJECTIVE: We assessed the hypothesis that exercise prevents fructose-induced increases in very-low-density lipoprotein (VLDL) triglycerides by decreasing the fructose conversion into glucose and VLDL-triglyceride and fructose carbon storage into hepatic glycogen and lipids. DESIGN: Eight healthy men were studied on 3 occasions after 4 d consuming a weight-maintenance, high-fructose diet. On the fifth day, the men ingested an oral (13)C-labeled fructose load (0.75 g/kg), and their total fructose oxidation ((13)CO2 production), fructose storage (fructose ingestion minus (13)C-fructose oxidation), fructose conversion into blood (13)C glucose (gluconeogenesis from fructose), blood VLDL-(13)C palmitate (a marker of hepatic de novo lipogenesis), and lactate concentrations were monitored over 7 postprandial h. On one occasion, participants remained lying down throughout the experiment [fructose treatment alone with no exercise condition (NoEx)], and on the other 2 occasions, they performed a 60-min exercise either 75 min before fructose ingestion [exercise, then fructose condition (ExFru)] or 90 min after fructose ingestion [fructose, then exercise condition (FruEx)]. RESULTS: Fructose oxidation was significantly (P < 0.001) higher in the FruEx (80% ± 3% of ingested fructose) than in the ExFru (46% ± 1%) and NoEx (49% ± 1%). Consequently, fructose storage was lower in the FruEx than in the other 2 conditions (P < 0.001). Fructose conversion into blood (13)C glucose, VLDL-(13)C palmitate, and postprandial plasma lactate concentrations was not significantly different between conditions. CONCLUSIONS: Compared with sedentary conditions, exercise performed immediately after fructose ingestion increases fructose oxidation and decreases fructose storage. In contrast, exercise performed before fructose ingestion does not significantly alter fructose oxidation and storage. In both conditions, exercise did not abolish fructose conversion into glucose or its incorporation into VLDL triglycerides. This trial was registered at clinicaltrials.gov as NCT01866215.

Power Consumption in Carbon Capture and Storage Systems (CCS) and Possibilities to Reduce Power Consumption with Variable Speed Drives

The aim of this master´s thesis is to study which processes increase the auxiliary power consumption in carbon capture and storage processes and if it is possible to reduce the auxiliary power consumption with variable speed drives. Also the cost of carbon capture and storage is studied. Data about auxiliary power consumption in carbon capture is gathered from various studies and estimates made by various research centres. Based on these studies a view is presented how the power auxiliary power consumption is divided between different processes in carbon capture processes. In a literary study, the operation of three basic carbon capture systems is described. Also different methods to transport carbon dioxide and carbon dioxide storage options are described in this section. At the end of the thesis processes that consume most of the auxiliary power are defined and possibilities to reduce the auxiliary power consumption are evaluated. Cost of carbon capture, transport and storage are also evaluated at this point and in the case that the carbon capture and storage systems are fully deployed. According to the results, it can be estimated what are the processes are where variable speed drives can be used and what kind of cost and power consumption reduction could be achieved. Results also show how large a project carbon capture and storage is if it is fully deployed.