No abstract

2021) Does the mode of anesthesia affect the feto-maternal outcome in category-1 caesarean section? A prospective non-randomized study comparing spinal versus general anesthesia,

No abstract

Previous examinations of building air free cooling using phase change material (PCM) plates were numerically conducted for specific arrangements/configurations of PCMs plates. Experimental investigation for models validations and comparison between the different configurations of PCMs are the shortages of these studies. The present research experimentally investigates the effects of the PCM plate's arrangements on the thermal characteristics of the charging and discharging processes. Parallel and staggered arrangements of different spaces between the plates were tested. The effect of plates' arrangements on the discharging time and quantity of PCM needed to fulfill the required free cooling are also investigated. The results showed that (a) in parallel arrangement, the discharge time decreases with decreasing spaces between PCM plates; (b) the discharge time in staggered arrangement is longer than that of parallel arrangement by 63%; (c) putting PCM plates on large numbers of rows increases the discharge time; (d) in staggered arrangement, the discharge time increases with decreasing spacing between PCMs plates; (e) the needed quantity of PCMs plates in staggered arrangement is lower than that of parallel arrangement by about 67%; and (f) generally, staggered arrangement with low spaces between PCMs plates is the optimum arrangement for air free cooling as it has the longest discharge time.

Energy storage systems designers normally use the thermophysical properties of phase change materials (PCMs) from the manufactures/suppliers data sheet. Unfortunately, sometimes PCMs systems do not behalf according to supplier data sheet, especially after cycling use. Designing systems based on these unrealistic data sheet make the system operates at off design conditions most of time. The problem is substantially appears in salt hydrates PCMs systems. In this short communication, a case study of such discrepancies in air free cooling is addressed. The system design was based on SP24E PCM data sheet, but results showed that liquids and solidus lines cannot shown on the temperature transient history during charging and discharging process, and complete solidification and melting could not be obtained. For further detailed investigations; differential scanning calorimeter (DSC) tests were conducted for SP24E PCM and completely different results than supplier data sheet were obtained DSC tests showed (a) a wide range of temperature variation during melting and solidifications, (b) phase change starts and ends at lower temperatures compared with supplier data sheet, and (c) phase change latent heat is lower than the one listed in supplier data sheet.