Industrial and Production Engineering

Heat transfer  is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy.(heat) between physical systems. Heat transfer is classified into various mechanisms, such as thermal conduction, thermal convection, thermal radiation, and transfer of energy by phase changes. Engineers also consider the transfer of mass of differing chemical species, either cold or hot, to achieve heat transfer. While these mechanisms have distinct characteristics, they often occur simultaneously in the same system. Heat conduction, also called diffusion, is the direct microscopic exchange of kinetic energy of particles through the boundary between two systems. When an object is at a different temperature from another body or its surroundings, heat flows so that the body and the surroundings reach the same temperature, at which point they are in thermal equilibrium. Such spontaneous heat transfer always occurs from a regi...

Pipes are said to be in parallel when they are so connected that the flow from a pipe branches or divides into two or more separate pipes and then reunite into a single pipe. Suppose a main pipe branched at section 1-1 into two pipes of lengths l1 and l2 and diameters d1 and d2 and unite again at a section 2-2 to form a single pipe. Then the two branch pipes are said to be connected in parallel. In this arrangement the total discharge Q divides into components Q1 and Q2 along the branch pipes such that – Q = Q1 + Q2 In this arrangement the loss of head from section 1-1 to section 2-2 is equal to the loss of head in any one of the branch pipes. hf = hf1 = hf2 Hence the total discharge Q divides into components Q1 and Q2 satisfying the above equation. Similarly when a number of pipes be connected in parallel, then also, the total loss of head in the system is equal to the loss of head in any one of the pipes. Credit:- http://www.engineeringenotes.com/fluid...

Pipes are said to be in series if they are connected end to end (in continuation with each other) so that the fluid flows in a continuous line without any branching. The volume rate of flow through the pipes in series is the same throughout. Suppose a pipe line consists of a number of pipes of different sizes and lengths. Let d1, d2, d3 be the diameters of the component pipes. Let l1, l2, l3 be the lengths of these component pipes. Let v1, v2, v3 be the velocities in these pipes. Pipes connected in continuation as in this case are said to be connected in series. In this arrangement the rate of discharge Q is the same in all the pipes. Ignoring secondary losses the total loss of head is equal to the sum of the friction losses in the individual pipes.                                                               Equivalen...

An abrupt contraction is geometrically the reverse of an abrupt enlargement . Here also the streamlines cannot follow the abrupt change of geometry and hence gradually converge from an upstream section of the larger tube. However, immediately downstream of the junction of area contraction, the cross-sectional area of the stream tube becomes the minimum and less than that of the smaller pipe. This section of the stream tube is known as vena contracta, after which the stream widens again to fill the pipe. The velocity of flow in the converging part of the stream tube from Sec. 1-1 to Sec. c-c (vena contracta) increases due to continuity and the pressure decreases in the direction of flow accordingly in compliance with the Bernoulli’s theorem. In an accelerating flow,under a favourable pressure gradient, losses due to separation cannot take place. But in the decelerating part of the flow from Sec. c-c to Sec. 2-2, where the stream tube expands to fill the pipe, losses take place in th...

Loss due to sudden enlargement If the cross-section of a pipe with fluid flowing through it, is abruptly enlarged at certain place, fluid emerging from the smaller pipe is unable to follow the abrupt deviation of the boundary. The streamline takes a typical diverging pattern. This creates pockets of turbulent eddies in the corners resulting in the dissipation of mechanical energy into intermolecular energy. Basic mechanism of this type of loss The fluid flows against an adverse pressure gradient. The upstream pressure p1 at section a-b is lower than the downstream pressure p2 at section e-f since the upstream velocity V1 is higher than the downstream velocity V2 as a consequence of continuity. The fluid particles near the wall due to their low kinetic energy cannot overcome the adverse pressure hill in the direction of flow and hence follow up the reverse path under the favourable pressure gradient (from p2 to p1). This creates a zone of recirculating flow with turbulent eddies ...

In fluid flow, friction loss (or skin friction) is the loss of pressure or “head” that occurs in pipe or duct flow due to the effect of the fluid's viscosity near the surface of the pipe or duct. In mechanical systems such as internal combustion engines, the term refers to the power lost in overcoming the friction between two moving surfaces, a different phenomenon. In the following discussion, we define volumetric flow rate V̇ (i.e. volume of fluid flowing)  V̇ = πr2v where r = radius of the pipe (for a pipe of circular section, the internal radius of the pipe). v = mean velocity of fluid flowing through the pipe. A = cross sectional area of the pipe. In long pipes, the loss in pressure (assuming the pipe is level) is proportional to the length of pipe involved. Friction loss is then the change in pressure Δp per unit length of  pipe   L {\displaystyle {\frac {\Delta p}{L}}.} When the pressure is expressed in terms of the equivalent height of a column of th...

The  hydraulic gradient  is a vector gradient between two or more hydraulic head measurements over the length of the flow path. For groundwater, it is also called the 'Darcy slope', since it determines the quantity of a Darcy flux or discharge. It also has applications in open-channel flow where it can be used to determine whether a reach is gaining or losing energy. A dimensionless hydraulic gradient can be calculated between two points with known head values as: {\displaystyle i={\frac {dh}{dl}}={\frac {h_{2}-h_{1}}{\mathrm {length} }}} where {\displaystyle i}  is the hydraulic gradient (dimensionless), {\displaystyle dh}  is the difference between two hydraulic heads (Length, usually in m or ft), and {\displaystyle dl}  is the flow path length between the two piezometers (Length, usually in m or ft) The hydraulic gradient can be expressed in vector notation, using the del operator. This requires a hydraulic head field,...

Pipe flow, a branch of hydraulics and fluid mechanics, is a type of liquid flow within a closed conduit (conduit in the sense of a means of containment). The other type of flow within a conduit is open channel flow. These two types of flow are similar in many ways, but differ in one important aspect. Pipe flow does not have a free surface which is found in open-channel flow. Pipe flow, being confined within closed conduit, does not exert direct atmospheric pressure, but does exert hydraulic pressure on the conduit. Not all flow within a closed conduit is considered pipe flow. Storm sewers are closed conduits but usually maintain a free surface and therefore are considered open-channel flow. The exception to this is when a storm sewer operates at full capacity, and then can become pipe flow. Energy in pipe flow is expressed as head and is defined by the Bernoulli equation. In order to conceptualize head along the course of flow within a pipe, diagrams often contain a hydraulic grade ...

A fluid flowing past the surface of a body exerts a force on it. Lift is the component of this force that is perpendicular to the oncoming flow direction. It contrasts with the drag force, which is the component of the force parallel to the flow direction. Lift conventionally acts in an upward direction in order to counter the force of gravity, but it can act in any direction at right angles to the flow. If the surrounding fluid is air, the force is called an aerodynamic force. In water or any other liquid, it is called a hydrodynamic force. Dynamic lift is distinguished from other kinds of lift in fluids. Aerostatic lift or buoyancy, in which an internal fluid is lighter than the surrounding fluid, does not require movement and is used by balloons, blimps, dirigibles, boats, and submarines. Planing lift, in which only the lower portion of the body is immersed in a liquid flow, is used by motorboats, surfboards, and water-skis. A fluid flowing past the surface of a body exerts a f...

In fluid dynamics,  drag  (sometimes called  air resistance , a type of friction,  or  fluid resistance , another type of friction or fluid friction) is a force  acting opposite to the relative motion of any object moving with respect to a surrounding fluid.  This can exist between two fluid layers (or surfaces) or a fluid and a solid  surface. Unlike other resistive forces, such as dry friction,  which are nearly independent of velocity, drag forces depend on velocity.  Drag force is proportional to the velocity for a laminar flow  and the squared velocity for a turbulent flow.  Even though the ultimate cause of a drag is viscous friction, the turbulent drag is independent of viscosity.  Drag forces always decrease fluid velocity relative to the solid object in the fluid's path.  Types of drag are generally divided into the following categories: (i) Parasitic drag,  consisting of (a) ...