Results of heating mode performance tests of a solar-assisted heat pump

The performance of a heat pump, utilizing 8.16 square meters of low-cost solar collectors as the evaporator in a Freon-114 refrigeration cycle, was determined under actual insolation conditions during the summer and fall of 1976. C.O.P.'s (coefficient of performance) greater than 3 were obtained with condensing temperatures around 78 C and evaporating temperatures around 27 C. Ambient temperatures were about 3 C above evaporating temperatures. Similar performance levels were obtained at other insolation and temperature conditions. Experience with the system has identified some component and system changes which should increase the obtainable C.O.P. to about 4.0. These are described along with the system's design rationale. The accumulated data are presented as an appendix

An economic and performance design study of solar preheaters for domestic hot water heaters in North Carolina

The performance and estimated material costs for several solar preheaters for domestic hot water heaters using isolation levels present in North Carolina are presented. The effects of monthly variations in isolation and the direction of incident radiation are included. Demand is assumed at 13 gallons (49.2 liters) per day per person. The study shows that a closed circulation system with 82 gallons (310 liters) of preheated storage and 53.4 cu ft (4.94 cu m) of collector surface with single cover can be expected to cost about $800 and to repay it capital cost and interest (at 8%) in 5.2 years, assuming present electric rates increase at 5% per year

An analytical investigation of the performance of solar collectors as nighttime heat radiators in airconditioning cycles

It was found that if the upper and lower ends of a collector were opened, large free convention currents may be set up between the collector surface and the cover glass(es) which can result in appreciable heat rejection. If the collector is so designed that both plates surfaces are exposed to convection currents when the upper and lower ends of the collector enclosure are opened, the heat rejection rate is 300 watts sq m when the plate is 13 C above ambient. This is sufficient to permit a collector array designed to provide 100 percent of the heating needs of a home to reject the accumulated daily air conditioning load during the course of a summer night. This also permits the overall energy requirements for cooling to be reduced by at least 15 percent and shift the load on the utility entirely to the nighttime hours

Automated design of minimum drag light aircraft fuselages and nacelles

The constrained minimization algorithm of Vanderplaats is applied to the problem of designing minimum drag faired bodies such as fuselages and nacelles. Body drag is computed by a variation of the Hess-Smith code. This variation includes a boundary layer computation. The encased payload provides arbitrary geometric constraints, specified a priori by the designer, below which the fairing cannot shrink. The optimization may include engine cooling air flows entering and exhausting through specific port locations on the body

The effect of seaweed meal on yolk colour

Could seaweed, plentiful on local beaches, be used to improve egg yolk colour? This article gives the results of experiments at the Department\u27s Poultry Research Station

Primjena visokotemperaturne DTA za mikrolegirane čelike

Paper deals with investigation of phase transitions temperatures for selected real grades of micro-alloyed steels. Temperatures of characteristic phase transitions were obtained using Setaram SETSYS 18TM. The DTA technique was selected for the study of micro-alloyed steels. Temperatures of phase transitions (liquidus, solidus etc.) were obtained. Influence of admixed and alloyed elements on shift of temperatures was investigated. Resulting data were compared with temperatures of phase transitions of Fe-C, Fe-Mn systems and with temperatures calculated according to relations published in available literature. Thermodynamic-kinetic solidification model IDS was used to calculate characteristic equilibrium temperatures of investigated systems.Članak se bavi studijom faznih transformacija odabranih mikrolegiranih čelika. Temperaturne karakteristike faznih transformacija su istraživane rabljenjem laboratorijskog sustava Setaram SETSYS-18TM. DTA tehnika je odabrana za studij mikrolegiranih čelika. Temperature faznih transformacija (likvidus, solidus itd.) su dobivene. Istraživan je utjecaj primjesa i legirajućih elemenata na promjene temperatura faznih transformacija. Dobiveni experimentalni rezultati su bili uspoređeni s temperaturama faznih transformacija sistema Fe-C, Fe-Mn a i s temperaturama izračunatih iz dostupne literature. Termodinamičkokinetički model skrućivanja IDS je rabljen za izračun karakterističnih ravnotežnih temperatura faznih transformacija istraživanih sustava

Comparison of measured and calculated thermophysical properties of nickel super-alloys

Three real grades of nickel super-alloys (IN 713LC, IN 738LC and IN 792-5A) were investigated and values of temperatures of phase transformations and latent heats of melting were obtained. All investigated quantities are very important for thermodynamic and kinetic modelling. Moreover, these data are also valuable for a lot of software used for technological processes modelling. Experimental values were obtained using Differential Thermal Analysis (DTA) measurements. Calculations were performed using Thermo-Calc 3.1 software with the use of three different databases (SSOL5, TTNI8 and TCNI6). Comparison and discussion of experimental and calculated data was performed

Termofizikalna i strukturalna studija IN 792-5A niklove superlegure

The presented paper deals with study of phase transformations temperatures of nickel based superalloy IN 792-5A with application of DTA – method and use of experimental laboratory system for simultaneous thermal analysis SETARAM Setsys 18TM. Samples taken from as-received state of superalloy were heated with controlled ramp rates (1, 5, 10 and 20 °C•min-1) and immediately after melting they were cooled with the same controlled ramp rate. The samples before and after DTA-analysis were also subjected to the phase analysis with use of scanning electron microscopy on the microprobe (JCXA 733) equipped with energy dispersive analyser EDAX (EDAM 3).Rad daje studiju temperature faznih transformacija niklove superslitine IN792-5A primjenom DTA metode te eksperimentalnog laboratorijskog sustava za simulaciju termalne analize SETARAM Setsys 18TM. Uzorci su uzeti iz početnog stanja legure i održavani definiranim brzinama (1, 5, 10 i 20 °C•min-1) i poslije ohlađeni kontroliranim brzinama. Uzorci su prije i poslije DTA analiza bili predmet fazne analize s primjenom skeninga elektronske mikroskopije (JCXA 733) dopunjeno s energi disperznom analizom EDAX (EDAM 3)

Human Galectins Induce Conversion of Dermal Fibroblasts into Myofibroblasts and Production of Extracellular Matrix: Potential Application in Tissue Engineering and Wound Repair

Members of the galectin family of endogenous lectins are potent adhesion/growth-regulatory effectors. Their multi-functionality opens possibilities for their use in bioapplications. We studied whether human galectins induce the conversion of human dermal fibroblasts into myofibroblasts (MFBs) and the production of a bioactive extracellular matrix scaffold is suitable for cell culture. Testing a panel of galectins of all three subgroups, including natural and engineered variants, we detected activity for the proto-type galectin-1 and galectin-7, the chimera-type galectin-3 and the tandem-repeat-type galectin-4. The activity of galectin-1 required the integrity of the carbohydrate recognition domain. It was independent of the presence of TGF-beta 1, but it yielded an additive effect. The resulting MFBs, relevant, for example, for tumor progression, generated a matrix scaffold rich in fibronectin and galectin-1 that supported keratinocyte culture without feeder cells. Of note, keratinocytes cultured on this substratum presented a stem-like cell phenotype with small size and keratin-19 expression. In vivo in rats, galectin-1 had a positive effect on skin wound closure 21 days after surgery. In conclusion, we describe the differential potential of certain human galectins to induce the conversion of dermal fibroblasts into MFBs and the generation of a bioactive cell culture substratum. Copyright (C) 2011 S. Karger AG, Base

Determination of solidus and liquidus temperatures for S34MnV steel grade by thermal analysis and calculations

The paper is devoted to the comparison of the results in the frame of solidus and liquidus temperatures obtained by thermo analytical methods with the generally used empirically based formulas and thermo dynamical Computherm software. The series of thermal analysis measurements of high temperature phase transformations of real steel grade (S34MnV) under conditions of two analytical devices (Netzsch STA 449 F3 Jupiter; Setaram Multi High Temperature Calorimeter (MHTC)) were carried out. Two thermo analytical methods were used (DSC and Direct Thermal Analysis). The different weight of samples was used (2,6 g; 23 g). The liquidus and solidus temperatures for close to equilibrium conditions during heating (DSC: 1 °C/min; 2 °C/min) and during cooling (Direct Thermal Analysis: 1 °C/min) were determined and compared. Then, the discussion on the different values obtained by experiments and empirically based calculation is realised