Effects of Cross Wind Conditions on Efficiency of Heller Dry Cooling Tower

Performance of a Heller cooling tower under wind conditions has been investigated by measuring wind velocity and its direction around the tower and inlet and outlet water flow rates and temperatures. Results show that air suction at the tower prevents flow separation at its periphery. The tower front cooling sectors experience better airflow distribution compared to sectors parallel to wind direction, which improves their thermal performance by about 20% compared to still-air conditions. Airflow pattern around the tower at different distances shows that wind tangential velocity at corner sectors is four times the velocity at the reference point, decreasing air pressure and tower suction.     

A computational study of non-Fourier temperature distribution in HIFU ablation of 3D liver tumor

Journal of Thermal Analysis and Calorimetry - So far, many researches have been done on temperature distribution due to thermal therapy. In these studies, the temperature field is obtained using...     

Solid phase microextraction using new sol–gel hybrid polydimethylsiloxane-2-hydroxymethyl-18-crown-6-coated fiber for determination of organophosphorous pesticides

A new sol–gel hybrid coating, polydimethylsiloxane–2-hydroxymethyl-18-crown-6 (PDMS–2OHMe18C6) was prepared in-house for use in solid phase microextraction (SPME). The three compositions produced were assessed for its extraction efficiency towards three selected organophosphorus pesticides (OPPs) based on peak area extracted obtained from gas chromatography with electron capture detection. All three compositions showed superior extraction efficiencies compared to commercial 100 μm PDMS fiber. The composition showing best extraction performance was used to obtain optimized SPME conditions: 75 °C extraction temperature, 10 min extraction time, 120 rpm stirring rate, desorption time 5 min, desorption temperature 250 °C and 1.5% (w/v) of NaCl salt addition. The method detection limits (S/N = 3) of the OPPs with the new sol–gel hybrid material ranged from 4.5 to 4.8 ng g⁻¹, which is well below the maximum residue limit set by Codex Alimentarius Commission and European Commission. Percentage recovery of OPPs from strawberry, green apple and grape samples with the new hybrid sol–gel SPME material ranged from 65 to 125% with good precision of the method (%RSD) ranging from 0.3 to 7.4%.