Experimental investigation of paraffin nano-encapsulated phase change material on heat transfer enhancement of pulsating heat pipe

Journal of Thermal Analysis and Calorimetry - In this study, a mixture of nano-encapsulated phase change materials in water has been used as the working fluid in a pulsating heat pipe in order to...     

BINOL Aza Macrocycle Derivatives: Synthesis of Dinaphthosulfone Aza Macrocycles Using p-Toluenesulfonic Acid (p-TsOH) in Methanol as an Efficient Route and Evaluation of Their 1H NMR Spectra

Dinaphthosulfone aza macrocycles were synthesized from the reaction of diamines and dinaphthosulfone diester (1,1′-sulfoxobis-(2-naphthoxy(2-methyl acetate))) in methanol in the presence of catalytic amounts of para toluenesulfonic acid (p-TsOH). Dinaphthosulfone diester (1,1′-sulfoxobis-(2-naphthoxy(2-methyl acetate))) was synthesized from the corresponding dinaphthosulfide diester and hydrogen peroxide in formic acid at room temperature. Dinaphthosulfide diester was prepared from initial dinaphtholsulfide diol (1,1′-thio bis(2-hydroxy naphthalene)) and methylchloroacetate. ¹H NMR spectroscopy showed the unusual splittings for these dinaphthosulfone aza macrocycles, and this finding could be proposed as the role of tetrahedral structure of sulfone functional group, hydrogen bonding in the cavity and size of macrocycle.     

A Novel Cutting Strategy for Measuring Two Components of Residual Stresses Using Slitting Method

An exact knowledge of residual stresses that exist within the engineering components is essential to maintain the structural integrity. All mechanical strain relief (MSR) techniques to measure residual stresses rely on removing a section of material that contains residual stresses. Therefore, these techniques are destructive as the integrity of the components is compromised. In slitting method, as a MSR technique, a slot with an increasing depth is introduced to the part incrementally that results in deformations. By measuring these deformations the residual stress component normal to the cut can be determined. Two orthogonal components of residual stresses were measured using the slitting method both experimentally and numerically. Different levels of residual stresses were induced into beam shaped specimens using quenching process at different temperatures. The experimental results were then compared with those numerically predicted. It was shown that while the first component of residual stress was being measured, its effect on the second direction that was normal to the first cut was inevitable. Finally, a new cutting configuration was proposed in which two components of residual stresses were measured simultaneously. The results of the proposed method indicated a good agreement with the conventional slitting.