Numerical study on heat transfer and flow resistance characteristics of multi-head twisted spiral tube

A numerical calculation model of multihead twisted spiral tube (MTST) was established. In the range of Reynolds number from 5000 to 35000, the influence of different twisted structure on the flow and heat transfer characteristics of the MTST was studied by numerical calculation. Numerical calculation results indicate that the Nusselt number and friction coefficient increase with the increase in the ratio of outside and inside diameter of the cross-section, the increase in the number of twisted nodes, and the increase in the number of twisted spiral tube heads. Under the condition of the same spiral structure and the same hydraulic diameter, the heat transfer performance of the MTST is better than that of the spiral smooth tube. In addition, through artificial neural network (ANN) analysis, the ratio of outside and inside diameter of the cross-section, number of twisted nodes, and the number of twisted spiral tube heads were optimized to promote the comprehensive heat transfer performance. The performance evaluation criterion is the highest when the ratio of outside and inside diameter of the cross-section is 25/22.5, the number of twisted nodes is 3, and the number of twisted spiral tube heads is 3, which is 1.849 of the spiral smooth tube.

Improving thermal performance using Al2O3-water nanofluid in a double pipe heat exchanger filling with porous medium

A double pipe heat exchanger is significant device for many industrial applications. In this paper, an experimental study using both porous media and nanofluid to enhance heat transfer in a double pipe heat exchanger is performed. The test rig has been fabricated with inner copper pipe of 1.10 m length, 16 mm, and 14 mm outside and inside diameter, respectively. While, the outer PVC pipe is 1 m length, 31 mm, and 27 mm outside and inside diameter, respectively. The inner pipe has been filling with 3 mm diameters of steel balls porous media. The experimental tests were performed utilizing alumina nanofluid (Al2O3-water) with two volume concentrations 0.5% and 1%. The volume flow-rates are in the range of (2-5) Lpm and 10 Lpm through inner and outer pipe, respectively. It was conducted with a constant 28?C inlet temperature of cold fluid-flow inside the inner pipe and 50?C inlet temperature of hot fluid-flow inside the outer pipe. Results indicated that the heat transfer enhanced as nanofluid volume concentrations and volume flow-rates increase. It was observed that effectiveness increases as increase of flow-rate and nanofluid concentrations.

Kajian Potensi Air Pengerak Pompa Hidram untuk Mengairi Sawah di Daerah Pakandangan Kabupaten Padang Pariaman

Energy is needed in mobilizing a mechanism both electric energy and energy derived from fossils. Hydram pump is a device to raise water from a low place to a high place by utilizing water impacts without using renewable energy. In Pakandangan, Padang Pariaman Regency, there is a water source that cannot be utilized to flow through the rice fields around 10 Ha. Because the rice fields are higher with water sources. The methodology is to survey the location and design the dimensions of the hydram pump. The results obtained head data height of incoming water is 2.5 meters, the height of water lift to the shelter is 7 meters the flow of water entering the pump is 25 lt / sec. The dimensions of the pump are the result of the design of a hydram 1 size with an inside diameter of 2 inches