one way to increase the heat transfer is to use perforated twisted tapes with different hole diameters, which largely improve heat transfer with an increase in the heat transfer area at the constant volume and more mixed flow. in the previous studies, the effect of nanofluids with perforated twisted tapes is less studied. in this work, the performance of water / iron oxide nanofluid in a double...

When evaluating single walled pipe vs. double walled pipe systems, one must consider two important types of failures: 'functional failure' and 'containment failure'. A functional failure is defined as pipeline system damage without loss of product containment integrity to the environment. A containment failure is defined as pipeline system damage with loss of product containment integrity, that...

Flow-induced pulsations in resonant pipe systems with two closed side branches in cross configuration are considered. These pulsations, commonly observed in many technical applications, are self-sustained aeroacoustic oscillations driven by the instability of the flow along the closed branches. Detuning of the acoustic resonator is often considered as a possible remedial measure. Although this ...

The elastic-plastic behavior of the material is considered to analyze the effect of an external circumferential crack on a pipe with thickness transition and double slopes. Using the extended finite element method (XFEM), the J-integral of 3D cracks were investigated and compared between straight pipes and pipes with thickness transition and different slopes. Considering internal press...

in this work, the characteristics of flow and heat transfer of a fluid containing nano particles of aluminum oxide with the water volume fraction (0.1-0.2-0.3)(v/v) percent of the reports. the overall heat transfer coefficient, heat transfer and the average heat transfer fluid containing nano water - aluminum oxide in a horizontal double pipe counter flow heat exchanger under turbulent flow con...

if an air flow is injected into a liquid fluid, many ambulant air bubbles are formed inside the fluid. air bubbles move inside the liquid fluid because of the buoyancy force, and the mobility of these air bubbles makes sizable commixture and turbulence inside the fluid. this mechanism was employed to enhance the heat transfer rate of a horizontal double pipe heat exchanger in this paper. howeve...

If an air flow is injected into a liquid fluid, many ambulant air bubbles are formed inside the fluid. Air bubbles move inside the liquid fluid because of the buoyancy force, and the mobility of these air bubbles makes sizable commixture and turbulence inside the fluid. This mechanism was employed to enhance the heat transfer rate of a horizontal double pipe heat exchanger in this paper. Howeve...

The using of double heat pipe based heat exchanger (HPHX) in a conventional fully fresh air air-conditioning (AC) system was examined in the present study. The fabricated HPHXs were tested under the actual conditions and the measured data were used to study the performance of the existing AC system (System A) and AC system equipped with the double HPHX (System B) for a yearly operation through ...

In this paper we constructed a class of double length hash functions which are maximally secure i.e. the birthday attack is the best possible attack. Recently, Joux [6] in Crypto-04 showed a multicollision attack on the classical iterated hash function which can be used to get the collision on the concatenated double length hash functions. Very recently, Lucks [10] also designed a double-pipe h...