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Hydronic balancing, also called hydraulic balancing, is the process of optimizing the distribution of water in a building's hydronic heating or cooling system by equalizing the system pressure. In a balanced system every radiator is set to receive the proper amount of fluid in order to provide the intended indoor climate at optimum energy ...
In a variable primary chilled-water system, the design flow rate is determined by the water flow velocity in the tube of the coils. At typical conditions, 6–7 feet per second (1.8–2.1 m/s) Maximum 12 ft/s (3.7 m/s) Minimum 1.5 ft/s (0.46 m/s) (based on a Reynolds number of 7500) Minimum flow is typically 50% or less of the design flow. [1]
A simplified version of the definition is: The k v factor of a valve indicates "The water flow in m 3 /h, at a pressure drop across the valve of 1 kgf/cm 2 when the valve is completely open. The complete definition also says that the flow medium must have a density of 1000 kg/m 3 and a kinematic viscosity of 10 −6 m 2 /s, e.g. water. [clarify]
Williams, Gardner Stewart; Hazen, Allen (1920), Hydraulic tables: the elements of gagings and the friction of water flowing in pipes, aqueducts, sewers, etc., as determined by the Hazen and Williams formula and the flow of water over sharp-edged and irregular weirs, and the quantity discharged as determined by Bazin's formula and experimental ...
At cross section 1, the mean flow velocity is equal to v 1, the pressure is p 1 and the cross-sectional area is A 1. The corresponding flow quantities at cross section 2 – well behind the expansion (and regions of separated flow ) – are v 2 , p 2 and A 2 , respectively.
In fluid dynamics, dynamic pressure (denoted by q or Q and sometimes called velocity pressure) is the quantity defined by: [1] = where (in SI units): q is the dynamic pressure in pascals (i.e., N/m 2, ρ (Greek letter rho) is the fluid mass density (e.g. in kg/m 3), and; u is the flow speed in m/s.
The choked velocity is a function of the upstream pressure but not the downstream. Although the velocity is constant, the mass flow rate is dependent on the density of the upstream gas, which is a function of the upstream pressure. Flow velocity reaches the speed of sound in the orifice, and it may be termed a sonic orifice.
where h f is the head loss due to friction, calculated from: the ratio of the length to diameter of the pipe L/D, the velocity of the flow V, and two empirical factors a and b to account for friction. This equation has been supplanted in modern hydraulics by the Darcy–Weisbach equation, which used it as a starting point.