Discussion of Hydraulic Calculation Methods for Hot Water Heating Direct Return System

2013 ◽  
Vol 353-356 ◽  
pp. 3049-3053
Author(s):  
Yong Zheng Fu ◽  
Yao Xiong ◽  
Hui Hui Liu
Keyword(s):  
Engineering Design ◽  
Constant Temperature ◽  
Calculation Method ◽  
Temperature Drop ◽  
Hot Water ◽  
Hydraulic Calculation ◽  
Calculation Methods ◽  
Water Heating ◽  
The Common ◽  
Hydraulic Balance

For hot water heating direct return system, the common hydraulic calculation method in engineering design is constant temperature drop method,which is calculated from the farthest riser loop. Due to the limit of the minimum pipe size, the method is usually difficult to achieve the hydraulic balance for every riser loop, and it needs the utilization of valves to meet the need. In this paper, through a calculation example, it has explained that every riser loop is very easy to achieve hydraulic balance without the utilization of valves when the system is calculated from the nearest riser loop. Besides, the calculation order of this method has been given.

scholarly journals The problem of hydraulic calculation of pressure distribution pipelines

2021 ◽  
Vol 6 (7 (114)) ◽  
Author(s):  
Volodymyr Cherniuk ◽  
Roman Hnativ ◽  
Oleksandr Kravchuk ◽  
Vadym Orel ◽  
Iryna Bihun ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
Flow Rate ◽  
Calculation Method ◽  
Fluid Motion ◽  
Hydraulic Calculation ◽  
Calculation Methods ◽  
Production Technologies ◽  
The Right ◽  
Longitudinal Slot ◽  
Resistance Coefficients

Most production technologies require a uniform flow path of liquid from pressure distribution pipelines. To achieve this goal, it is proposed to introduce polymer additives into the liquid flow or to use converging distribution pipelines with a continuous longitudinal slot in the wall. To reduce the uneven operation of the distribution pipeline during discrete liquid dispensing, it is proposed to use cylindrical output rotary nozzles with a lateral orthogonal entry of the jet into the nozzle. The problem is the lack of methods for accurate hydraulic calculation of the operation of distribution pipelines. Adequate calculation methods are based on differential equations. Finding the exact solution of the differential equation of fluid motion with variable path flow rate for perforated distribution pipelines is urgent, because it still does not exist. The available calculation methods take into account only the right angles of separation of the jets from the flow in the distribution pipeline. These methods are based on the assumption that the coefficient of hydraulic friction and the coefficient of resistance of the outlets are constant along the flow. A calculation method is proposed that takes into account the change in the values of these resistance coefficients along the distribution pipeline. The kinematic and physical characteristics of the flow outside the distribution pipeline are also taken into account. The accuracy of calculating the value of the flow rate of water distributed from the distribution pipeline has been experimentally verified. The error in calculating the water consumption by the method assuming that the values of the resistance coefficients are unchanged along the distribution pipeline reaches 18.75 %. According to the proposed calculation method, this error does not exceed 6.25 %. However, both methods are suitable for the design of pressure distribution pipelines, provided that the jet separation angles are straight. Taking into account the change from 90° to 360° of the angle of separation of the jets from the flow in the distribution pipeline will expand the scope and accuracy of calculation methods.

Study on the Calculation Method of Soil-Nailing for High Soil Slope Based on the Logarithmic Spiral Slippery Fracture

2011 ◽  
Vol 261-263 ◽  
pp. 1709-1713
Author(s):  
Meng Yang ◽  
Xiao Min Liu
Keyword(s):  
Mathematical Model ◽  
Stability Analysis ◽  
Engineering Design ◽  
Calculation Method ◽  
Logarithmic Spiral ◽  
Soil Nailing ◽  
Soil Slope ◽  
Mode Pattern ◽  
Shear Function

This paper introduces a new failure mode pattern of soil slope – the logarithmic spiral slippery fracture. A mathematical model for the logarithmic spiral slippery fracture is established, taking the anti-shear function of the soil-nailing into consideration. The shear of soil-nailing, axial force, and the safety coefficients based on the limiting equilibrium method are derived, leading to an accurate stability analysis of the strengthening of soil slope. A case study shows that the anti-shear function of the soil-nailing can be significant and should not be ignored in engineering design.

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