Characteristics of Some New Generation Refrigerants with Low GWP

AbstractIn the present study, a comparison was considered about some characteristics of new generation low GWP value gases most of which are at the trial stage. Hydrofluoro-olefin (HFO) based mixed gases having low GWP value were investigated as alternatives to different four refrigerants used commonly in refrigerating and air conditioning equipments. In the study, R450A, R513A, R1234yf and R1234ze(E) gases were used instead of R134a; DR-33, L40, DR-7 and R448A were used instead of R404A; DR-5 and R447A were used instead of R410A; and N20 and R444B refrigerants were used as alternatives to R22. Refrigerants were compared within their own groups in terms of liquid density and viscosity properties

Prikaz eksperimentalne metode za mjerenje srednje brzine oscilirajućeg toka u cijevi pomoću anemometra s toplom niti

The utilization of constant temperature anemometry (CTA) system for the measurement of mean oscillating velocity of air at negligible compressibility is discussed in this paper. The measurements were conducted at a station of self-excited oscillations in a circular cross sectional pipe following the collapse of the elastic test tube of a Starling resistor in a flow Reynolds number range of 7,000 ≤ Re ≤ 94,000. The cross-sectional traverse of the hot-wire probe at the measurement station in a frequency (f) range of 13Hz ≤ f ≤ 107Hz were conducted. The cross sectional oscillating velocity profile was determined by using the ensembled averages of oscillating velocity data. The position of the hot-wire probe corresponding to the mean axial oscillating velocity was determined to be approximately 0.755 of pipe radius from the centreline in the covered ranges of Re and f.U ovom radu je prikazana upotreba anemometra u načinu rada s konstantnom temperaturom za mjerenje srednjih oscilirajućih brzina zraka pri zanemarivoj stlačivosti. Mjerenja su vršena pri samopobudnim oscilacijama u cijevi kružnog poprečnog presjeka postavljene nakon prigušne Starling-ove cijevi, u rasponu Reynoldsove značajke 7 000 ? Re ? 94,000. Raspon frekvencija mjerne sonde je u rasponu 13Hz ? f ? 107Hz. Profil oscilirajućih brzina toka zraka u poprečnom presjeku cijevi je određen skupom uprosječenih podataka dobivenih mjerenjem. Pozicija mjerne sonde anemometra s toplom niti u odnosu na srednju aksijalnu brzinu toka zraka je određena da iznosi 0.755 radijusa cijevi od simetrale cijevi za navedene raspone Re značajke i frekvencije

Prikaz eksperimentalne metode za mjerenje srednje brzine oscilirajućeg toka u cijevi pomoću anemometra s toplom niti

The utilization of constant temperature anemometry (CTA) system for the measurement of mean oscillating velocity of air at negligible compressibility is discussed in this paper. The measurements were conducted at a station of self-excited oscillations in a circular cross sectional pipe following the collapse of the elastic test tube of a Starling resistor in a flow Reynolds number range of 7,000 ≤ Re ≤ 94,000. The cross-sectional traverse of the hot-wire probe at the measurement station in a frequency (f) range of 13Hz ≤ f ≤ 107Hz were conducted. The cross sectional oscillating velocity profile was determined by using the ensembled averages of oscillating velocity data. The position of the hot-wire probe corresponding to the mean axial oscillating velocity was determined to be approximately 0.755 of pipe radius from the centreline in the covered ranges of Re and f.U ovom radu je prikazana upotreba anemometra u načinu rada s konstantnom temperaturom za mjerenje srednjih oscilirajućih brzina zraka pri zanemarivoj stlačivosti. Mjerenja su vršena pri samopobudnim oscilacijama u cijevi kružnog poprečnog presjeka postavljene nakon prigušne Starling-ove cijevi, u rasponu Reynoldsove značajke 7 000 ? Re ? 94,000. Raspon frekvencija mjerne sonde je u rasponu 13Hz ? f ? 107Hz. Profil oscilirajućih brzina toka zraka u poprečnom presjeku cijevi je određen skupom uprosječenih podataka dobivenih mjerenjem. Pozicija mjerne sonde anemometra s toplom niti u odnosu na srednju aksijalnu brzinu toka zraka je određena da iznosi 0.755 radijusa cijevi od simetrale cijevi za navedene raspone Re značajke i frekvencije

Eksperimentalna analiza zračnog toka u sklopivim cijevima pri pojavi samopobudnih oscilacija

The experimental results of airflow through some collapsible tubes are analysed in this paper for the case of onset of self-excited oscillations without so much focusing on the mechanisms triggering the oscillations. The basic experimental measurements are the pressure values at both of upstream and downstream ends of the collapsible tube as well as velocity at downstream of the tube by means of a hot wire anemometer. The obtained results correspond to the instant at which oscillations appear. It has been established that the flow is substantially chaotic during the vigorous oscillations. The experimental data at the onset of self-excited oscillations was evaluated subsequently to obtain some non-dimensional parameters based on oscillating flow velocity, frequency, pressure drop through the collapsible tube and downstream transmural pressure. The variations of these parameters with some terms including all geometrical and mechanical characteristics of the collapsible tubes are presented. The diversity of experimental variables such as collapsible tube type, tube-wall thickness, tube length and flow rate which are varied in the investigation should be useful on account of having a general information about collapsible tube flow researches. It has been recognized that all of these variables considerably affected the behaviour (frequency, velocity, upstream and downstream pressure) of oscillations and conditions of their emergence. It can thereby be suggested that the specifications of the tube should be carefully considered in the collapsible tube flow investigations.U ovom radu se analizira eksperimentalne rezultate mjerenja zračnog toka kroz sklopive cijevi za slučaj samopobudnih oscilacija, bez mnogo razmatranja mehanizama koji pokreću oscilacije. Osnovna eksperimentalna mjerenja su vrijednosti tlaka na uzstrujnom i nizstrujnom kraju sklopive cijevi te brzina na nizstrujnom kraju mjerena pomoću anemometra s vrućom žicom. Dobiveni rezultati se podaudaraju do trenutka pojave oscilacija. Ustanovljeno je da je protok prilično kaotičan tijekom snažnih oscilacija. Eksperimentalni podaci pri nastanku samopobudnih oscilacija su naknadno evaluirani kako bi se dobilo neke bezdimenzijske parametre vezane uz brzinu oscilatornog protoka, frekvenciju, pad tlaka kroz sklopivu cijev i nizstrujni tlak kroz stijenku. Prikazane su varijacije tih parametara po nekim članovima izraza uključujući sve geometrijske i mehaničke karakteristike sklopivih cijevi. Raznolikost eksperimentalnih varijabli poput vrste cijevi, debljine stijenke cijevi, duljine cijevi i brzine protoka variranih u istraživanju trebala bi biti korisna zbog sadržanih općih informacija za istraživanja sklopivih cijevi. Prepoznato je da sve navedene varijable značajno utiču na svojstva (frekvenciju, brzinu, uzstrujni i nizstrujni tlak) oscilacija i uvjete njihovog pojavljivanja. Stoga se može preporučiti pažljivo razmatranje tehničkog opisa cijevi u istraživanjima sklopivih cijevi

An Investigation on the Utilization of R470A for Air-Conditioning Systems Towards 2025

The refrigerants with GWP > 750 will not be used in air conditioners according to the application of European Union restrictions that will become valid as of 2025. In this context, this study aims to investigate theoretically the utilization of the non-flammable and low-GWP refrigerant of R470A in the air conditioning system. In the analysis, R470A and R32 are compared for the evaporation temperatures of 5, 10, and 12°C while the condenser temperatures of 40 and 50°C. Although the COP of R470A is determined to be lower than R32 for a given situation of evaporation and condenser temperature, it can be safely used in systems requiring a higher amount of refrigerant charge due to its non-flammable property

Sexuality in young adult men aged 18-24 with epilepsy

WOS: 000323263500003The aim of this study was to determine the extent of sexual dysfunction in young male patients (18-24 years) with epilepsy. Forty-five male patients with epilepsy aged between 18 and 24, and forty-four age- matched healthy male volunteers were included in the study. Participants completed a battery of self-reported tests (ASEX: Arizona Sexual Experiences Scale, HADS: Hospital Anxiety and Depression Scale). Demographic and clinical variables were recorded. Serum total testosterone was measured between 8:00 and 10:00 a.m. in patients with epilepsy. Sexual function scores (sexual drive and penile erection) were higher in patients with epilepsy than those of the control group (p < 0.001 and p = 0.008, respectively). the difference between the mean total ASEX scores, which were 13.9 and 11.4 in patients with epilepsy and controls, respectively, was significant (p = 0.009). HAD anxiety scores were significantly higher in patients with epilepsy than controls (p = 0.01) (Table 2). HAD-depression scores of both groups were similar (p = 0.09). This study demonstrates that young male patients with epilepsy have lower levels of sexual activity and drive and more erectile problems. Impaired sexual function is associated with anxiety scores

Epileptic seizures in cerebral venous sinus thrombosis: Subgroup analysis of VENOST study

Purpose: The aim of this study is to evaluate the presence and prognostic impact of early seizures in cerebral venous sinus thrombosis patients (CVST).Method: VENOST is a retrospective and prospective national multicenter observational study. CVST patients with or without epileptic seizures (ES) were analyzed and compared in terms of demographic and imaging data, causative factors, clinical variables, and prognosis in a total of 1126 patients.Results: The mean age of the patients in the ES group was 39.73 +/- 12.64 and 40.17 +/- 14.02 years in the non-ES group (p > 0.05). Epileptic seizures were more common (76.6 %) in females (p < 0.001). Early ES occurred in 269 of 1126 patients (23.9 %). Epileptic seizures mainly presented in the acute phase (71.4 %) of the disease (p < 0.001). Majority of these (60.5 %) were in the first 24 h of the CVST. The most common neurological signs were focal neurologic deficits (29.9 %) and altered consciousness (31.4 %) in the ES group. Superior sagittal sinus (SSS) and cortical veins (CV) involvement were the most common sites of thrombosis and the mostly related etiology were found puerperium in seizure group (30.3 % vs 13.9 %). Patients with seizures had worse outcome in the first month of the disease (p < 0.001) but these did not have any influence thereafter.Conclusions: In this largest CVST cohort (VENOST) reported female sex, presence of focal neurological deficits and altered consciousness, thrombosis of the SSS and CVs, hemorrhagic infarction were risk factors for ES occurrence in patients with CVST