Phatthalung, Thailand
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Sakamatapan K.,King Mongkut's University of Technology Thonburi | Kaew-On J.,King Mongkut's University of Technology Thonburi | Kaew-On J.,Taksin University | Dalkilic A.S.,Yildiz Technical University | And 3 more authors.
International Journal of Heat and Mass Transfer | Year: 2013

In this study, the condensation heat transfer characteristics of R-134a flowing inside multiport minichannels were investigated. The multiport minichannel-tested tubes have 14 channels with a 1.1 mm hydraulic diameter, and eight channels with a 1.2 mm hydraulic diameter were designed as a counterflow tube-in-tube heat exchanger. The experiment was performed with mass fluxes of refrigerant between 340 and 680 kg/m2s, with 15, 20, and 25 kW/m 2 heat fluxes, and saturation temperatures of 35-45 C. The flow pattern for the experimental data was initially predicted using existing flow pattern maps. It could be noted that the annular flow pattern existed for most of the experimental data. Results showed that the average heat transfer coefficient increased with the increase of vapor quality, mass flux, and heat flux, but decreased as saturation temperature rose. When compared with two correlations obtained from condensation inside the multiport minichannels, the heat transfer coefficient could be predicted within an acceptable range. © 2013 Elsevier Ltd. All rights reserved.

Harding P.,Walailak University | Harding D.J.,Walailak University | Soponrat N.,Taksin University | Tinpun K.,Taksin University | And 2 more authors.
Australian Journal of Chemistry | Year: 2010

The reaction of ppaX {(4-X-phenyl)-pyridin-2-ylmethylene-amine; X = H, Me, Et, OMe, F, Cl, Br, and I} with [Ni(β-diketonate) 2(H2O)2] {β-diketonate = 1,3-diphenylpropanedionate (dbm), 2,2,6,6-tetramethyl-3,5-heptadionate (tmhd), or hexafluoroacetylacetonate (hfac)} yields a series of nickel complexes. X-ray crystallography reveals octahedral coordinated nickel centres with a cis arrangement of the -diketonate ligands. The β-diketonate ligands adopt 'planar' or 'bent' coordination modes, whereas the aryl ring of the ppa X ligand is twisted with respect to the pyridylimine unit. The electrochemical behaviour of the complexes reveals quasi-reversible or irreversible one-electron oxidation to Ni(iii) in the case of the [Ni(tmhd) 2(ppaX)] and [Ni(dbm)2(ppaX)] complexes, respectively. The peak potential for oxidation is dependent on the type of β-diketonate ligand but essentially independent of the substituent, X, on the ppaX ligand. The [Ni(β-diketonate) 2(ppaX)] complexes (X = F, Cl, Br, and I) also undergo ligand based reduction. © 2010 CSIRO.

Harding P.,Walailak University | Harding D.J.,Walailak University | Soponrat N.,Taksin University | Adams H.,University of Sheffield
Acta Crystallographica Section E: Structure Reports Online | Year: 2011

The title compound, [Ni(C5HF6O2)2(C 12H9BrN2)], the NiII atom exhibits a pseudo-octa-hedral coordination geometry. The structure packs throuh C - H⋯Br interactions, forming a hydrogen-bonded ladder. There are also strong hydrogen-bonding interactions between two of the O atoms of the Β-diketonate ligands and two H atoms on the pyridine ring of the Schiff base ligand.

Harding P.,Walailak University | Harding D.J.,Walailak University | Soponrat N.,Taksin University | Adams H.,University of Sheffield
Acta Crystallographica Section E: Structure Reports Online | Year: 2010

In the title complex, [Co(C5HF6O2) 2(C12H9BrN2)], the CoII atom exhibits a pseudo-octahedral coordination geometry, comprising two N-donor atoms from a bidentate chelate (4-bromophenyl)(2-pyridylmethylidene)amine (ppaBr) ligand [Co-N = 2.098 (2) and 2.209 (2) Å] and four O-donor atoms from two bidentate chelate 1,1,1,5,5,5-hexafluoropentane-2,4- dionate (hfac) ligands [Co-O range = 2.0452 (19)-2.0796 (19) Å]. The packing of the structure involves weak π-π inter-actions between the pyridyl and benzene rings of neighbouring ppaBr ligands [centroid-centroid distance = 3.928 (2) Å] and inter-actions between the Br atom on the ppaBr ligand and the hfac ligand [Br⋯C = 3.531 (2) Å].

Harding D.J.,Walailak University | Harding P.,Walailak University | Kivnang J.,Taksin University | Adams H.,University of Sheffield
Transition Metal Chemistry | Year: 2010

The cationic complexes, [TpRNi(bpym)]+ {Tp R = tris(3,5-diphenylpyrazolyl)borate, R = Ph2 1; tris(3- phenyl-5-methylpyrazolyl)borate, R = Ph,Me 2} were synthesized by reacting [TpRNiBr] (R = Ph2; Ph,Me)with bipyrimidine followed by subsequent addition of KPF6 in CH6Cl2. The green solids have been characterized by IR, UV-Vis and 1H NMR spectroscopy. Crystallographic studies of [TpPh,MeNi(bpym)]PF 6 reveal a five-coordinate square pyramidal nickel centre with a κ3-coordinated TpPh,Me ligand and a chelating bipyrimidine ligand. Cyclic voltammetric studies show irreversible reduction with the degree of reversibility dependent on the type of TpR ligand. © Springer Science+Business Media B.V. 2010.

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