The present study investigated the effect of wall roughness on velocity, cellular structure, and limits detonation propagation in tubes. Wall was effected by placing a wire spring into tube. Since diameter is small compared to tube diameter, spiral more representative than repeated orifice plates used majority previous studies. Detonation velocity determined from time-of-arrival ionization prob...

In this paper thermo-hydrodynamic characteristics were investigated experimentally for a new type shell-helical coiled tube heat exchanger used as storage tank of closed loop solar water heater system. Triple concentric helical coils made copper tubes (12.5mm OD and 10mm ID) with diameter (207, 152.2, 97mm) outer, middle inner respectively. The experiments carried out during clear sky days (Mar...

OBJECTIVE To determine the radiation doses and image quality of different dual-source computed tomography coronary angiography (CTCA) protocols tailored to the heart rate (HR) and body mass index (BMI) of the patients. MATERIALS AND METHODS Two hundred consecutive patients (68 women; mean age 61+/-9 years) underwent either helical CTCA with retrospective ECG-gating or sequential CT with prosp...

OBJECTIVE We wanted to evaluate the performance of prospective electrocardiogram (ECG)-gated axial scans for assessing coronary stents as compared with retrospective ECG-gated helical scans. MATERIALS AND METHODS As for a vascular model of the coronary artery, a tube of approximately 2.5-mm inner diameter was adopted and as for stents, three (Bx-Velocity, Express2, and Micro Driver) different...

The thermal performance of the evacuated tubes solar collector (ETSC) for heating water with and without helical tape inside is evaluated experimentally. effect employing in tube on mean temperature storage tank efficiency has been investigated under winter ambient conditions AL-Mussaib city-Babylon-Iraq January February 2021. results showed an improvement using tubes. maximum meat that recorde...

The present study was numerically inquired the heat transfer performance and fluid flow characteristic of a helical micro double-tube exchanger (HMDTHX) using finite volume method. tube length considered to be constantly equal 30 mm, 12 different configurations were modeled by changing in turn number pitch (P) for Reynolds numbers 50, 100, 150, 200. findings indicated that would enhance applyin...

In the second half of 1998, four manufacturers (GE, Siemens, Toshiba and Picker, now Philips) extended this concept by launching multi-slice CT scanners. All were 3rd generation helical scanners, with low voltage slip rings, capable of acquiring four CT slices in one x-ray tube rotation (see Fig. 1). Additional four-slice models have been introduced by Toshiba and GE. Some basic specifications ...