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The objective of the study was to investigate the effects of oil sources in the diet on milk yield, milk composition, and fatty acid (FA) profiles in mid-lactating dairy cows. Forty-eight Chinese Holstein dairy cows averaging 150 days in milk (DIM) at the start of the experiment (body weight = 596±19 kg; milk yield = 29.7±3.00 kg/d) were used in a completely randomized block design. The animals were assigned into four dietary treatments according to DIM and milk yield, and supplemented with no oil (control), 2% flaxseed oil (FSO), 2% soybean oil (SBO), and 2% oil from extruded soybeans (ESB). The experiment lasted nine weeks including the first week for adaptation. Milk yields, milk compositions (fat, protein, and lactose), and milk FA profiles were measured. Daily milk yield from cows fed with FSO, SBO, and ESB were higher than milk yield of the control cows (27.0, 27.0, and 26.5 vs. 25.4 kg/d). Milk fat percentage of the control cows was greater than those cows fed with oil-supplemented diets. However, increasing dietary fat content resulted with no change in fat-corrected milk yield. The FA profile of milk was changed by fat supplementation. Feeding oil reduced the proportion of both short-chain (C8:0 to C12:0) and medium-chain (C14:0 to C16:1) FAs, and increased the proportion of long-chain (≥C18:0) FAs in milk fat. Cis-9, trans-11 conjugated linoleic acid (CLA) in milk fat was increased from 0.38% for the control to 0.79, 1.51, and 1.56% of fat for the cows supplemented with FSO, SBO, and ESB, respectively. Feeding oils rich in linoleic acid (SBO and ESB) was more effective in enhancing cis-9, trans-11 CLA in milk fat than oils containing linolenic acid (FSO). There was a linear relationship between transvaccenic acid and cis-9, trans-11 CLA content in milk. Overall, feeding the FSO, SBO, and ESB diets increased monounsaturated and polyunsaturated fatty acids and decreased the saturated fatty acid in milk fat. [ABSTRACT FROM AUTHOR]

Numerical investigations were conducted to understand forced laminar fluid flow over coiled pipes with circular cross-section. The focus was addressed on exploring the convective heat transfer from conical and helical coils with comparative studies. The same numerical investigation method was applied to the two differentially coiled pipes (helical and conical) and for different Reynolds numbers corresponding to five cases of exterior flow arrangement. The results show better heat transfer performance for cases of conical coils where much flow turbulence was observed due to an effective flow arrangement. [ABSTRACT FROM AUTHOR]

An investigation was conducted to understand thermally fully developed convective transport phenomena induced by both electroosmosis and pressure gradients in a narrow parallel channel. A model was developed to describe the fluid flow and associated heat transport phenomena. Both the dimensionless temperature profile and the Nusselt number were obtained analytically with and without Joule heating with an investigation conducted to understand the importance of Joule heating and the ratio of the hydraulic flow rate to the electroosmotic flow rate. The emphasis of the comprehensive discussion is on understanding the physical significance of the singularities of the flow behavior and heat transfer. [ABSTRACT FROM AUTHOR]

An experimental facility was set up to study the flow and boiling heat transfer characteristics of water and methanol flowing through V-shape microchannels. The microchannels have hydraulic diameters ranging from 0.2 to 0.6 mm and V-shape groove angles 0 of 30 to 60°. Both the heat transfer and the pressure drop were affected by the thermofluid and geometric parameters such as liquid flow velocity, subcooling, and the hydraulic diameter and groove angle of the microchannels. The experiments indicted that there exists both an optimum hydraulic diameter and an optimum groove angle. The visualization experiments showed that, if there was a good seal between the glass cover and the microchanneled test plate, no bubbles were observed in the microchannels for flow boiling with heat fluxes as high as of the order of 106 W/m2, at which fully nucleate boiling with a large number of bubbles would be expected in conventional situations. Fluctuating liquid flow was induced in the microchannels when many bubbles formed in the inlet plenum. [ABSTRACT FROM PUBLISHER]

The forced-flow convection of water through rectangular microchannels having hydraulic diameters of 0.133-0.367 mm and aspect ratios of H/W = 0.333-1 was investigated experimentally. The flow friction was measured to analyze the heat transfer regimes and to explore the physical aspects of the connective heat transfer. The experimental measurements indicated that the upper bound of the laminar heat transfer regime occurred at a Reynolds number of 200-700, and fully turbulent connective heat transfer was reached at Reynolds numbers of 400-1,500. The transition Reynolds number diminished with the reduction of the microchannel dimension, and the transition range was observed to become smaller in magnitude. For the laminar heat transfer regime, the Nusselt number was found to be proportional to Re0.62while the turbulent heat transfer case exhibited a typical relationship between Nu and Re, but with a different empirical coefficient, CH,t. The geometric parameters were found to be important variables that could significantly affect the flow characteristics and heat transfer. The laminar connective heat transfer had a maximum value when the aspect ratio, H/W, was approximately equal to 0.75, and the turbulent heat transfer was optimal when the aspect ratio was in the range 0.5-0.75. [ABSTRACT FROM PUBLISHER]

Experiments were conducted to investigate the flow characteristics of water flowing through rectangular microchannels having hydraulic diameters of 0.133-0.367 mm and H/W ratios of 0.333-1. Experimental results indicated that the laminar flow transition occurred at Reynolds numbers of 200-700. This critical Re for the laminar transition was strongly affected by the hydraulic diameter, decreasing with corresponding decreases in the microchannel. In addition, the size of the transition range was diminished and fully developed turbulent flow also occurred at much lower Re. The friction behavior of both the laminar and turbulent flow was found to depart from the classical thermqfluid correlations. lite friction factor, f, was found to be proportional to Re−1.98 rather than Re for the laminar condition, and proportional to Re−1.72i for turbulent flow. The geometric parameters, hydraulic diameter, and H/W were found to be the most important parameters and had a critical effect on the flow. Generally, increasing the ratio H/W increases the friction factor. The reduction of the microchannel hydraulic radius decreases the friction factor significantly for a given H/W. There exists a special range of ratio H/W (approximately 0.5 mm) at which the experimental data are lower than the predictions obtained from classical correlations. Continued reduction of channel size increases the difference between fI,expf1,theo at REcri, and the quantity of fI,exp becomes smaller within the region adjacent to H/W = 0.5, and larger when H /Wis out of this region. [ABSTRACT FROM PUBLISHER]