Local losses in pipe flows principle change in flow velocity due to change in the geometry of a pipe system i. Working with a wide array of state, community, industry, and university partners, the u. Start the pump and wait until water flows through all the sections of the piping network and attains. Minor loss coefficients for storm drain modeling with swmm. It works with tecquipments digital hydraulic bench h1f. Energy losses due to frictional effects of pipe or duct material or due to a change in velocity within a fitting cause energy loss in flowing fluids.
Most pipe systems consist of considerably more than straight pipes. Numerical investigations of flow behavior and energy losses. Insulation can typically reduce energy losses by 90% and help ensure proper steam pressure at plant equipment. Just as certain aspects of the system can increase the fluids energy, there are components of the system that act against the fluid and reduce its. The head loss associated with a fluid flowing through a screen can easily be calculated using the energy equation. The knowledge of data of such transformation allows the determination. This guide is designed to help builders better understand and meet the hot water delivery system criteria as specified in the watersense new home specification watersense new home specification. The more circuitous is the path, the greater are the losses.
According to a 2005 report from the california energy commission, waterrelated energy consumption accounts for nearly 20 percent of all electricity water supply system losses in san diego county the waterenergy connection and opportunities to reduce future losses. The head loss of a pipe, tube or duct system, is the same as that produced in a straight pipe or duct whose length is equal to the pipes of the original systems plus the sum of the equivalent lengths of all the components in the system. Insulate steam distribution and condensate return lines. The valves are at the outlet to minimise flow disruption.
Water audits and water loss control for public water. Introduction local head losses occur in the pipes when there is a change in the area of the crosssection of the pipe enlargement, contraction, a change of the direction of the flow bends, and application of some devices on the pipe vanes. These losses are usually converted into head reductions in the direction of the flow. The phenomenon is likely to appear only in large diameter pipes andor at high reynolds numbers.
Energy losses in pipes used for the transportation of fluids water, petroleum etc. Numerical investigations of flow behavior and energy. To determine the loss factors for flow through a range of pipe fittings including bends, a contraction, an enlargement and a gatevalve. The major loss is that due to frictional resistance of the.
Therefore,a proper selection of fitting is essential. According to a 2005 report from the california energy commission, waterrelated energy consumption accounts for nearly 20 percent of all electricity water supply system losses in san diego county the water energy connection and opportunities to reduce future losses. The overall head loss for the pipe system consists of the head loss due to viscous effects in the straight pipes, termed the major loss and denoted hlmajor. Energy efficiency measures to consider the following list is a reference resource of energy efficiency measures eems to consider when performing an energy audit. These additional components add to the overall head loss of the system. Figure 5 shows the schematic layout of the pipe network to be used in the present study. Head loss in pipe flow major and minor losses me 322 lecture slides, winter 2007 gerald recktenwald. The article presents aspects related to the calculation of heat loss through the pipes of the interior central heating system. Water audits and water loss control for public water systems. Estimating energy consumption of mobile fluid power in the united states lauren a. Insulate pipes with no insulation or replace damaged insulation and apply for a cash rebate. This paper presents water heating energy use profiles with and without recirculation pump cycling during unoccupied hours.
The table shows typical heat loss from uninsulated steam distribution lines. Energy losses when a fluid is flowing through a pipe, the fluid experiences some resistance due to which some of the energy of the fluid is lost. Boilers bureau of energy efficiency 27 syllabus boilers. In reality, the head loss does not take place due to the sudden contraction but due to the sudden enlargement, which takes place just after venacontracta fig. Base on 1,000 ft for lean iron an steel pipes sheule 0 for pumping 0f water eletriity rate of 00 kwh an,0 operating hours annually combine pump an motor eieny of 0 courtesy of p barringer 1. A mobile, vertical panel featuring various pipe configurations to demonstrate flow and losses in different pipes fittings and valves. Local losses usually result from abrupt changes in velocity leading to eddy formation which extract energy from the mean flow.
A better sealing of these openings results in lower convective energy losses. Apparent losses represent a loss of revenue because the water is. Minor losses local pump tee valve outlet elbow inlet pipe b vena contracta flow separation at corner separated flow separated flow q pipe entrance or exit sudden expansion or contraction bends, elbows, tees, and other fittings valves, open or. By observation, the head loss is roughly proportional to the square of the flow rate in most engineering flows fully developed, turbulent pipe flow. Leaks from valves, external pipes, tubes or adjacent equipment can cause wet insulation. The energy losses due to pressure changes can be seen in every part of a hydraulic system due to the expansions, contractions, bends in pipes, pipe fittings, and obstructions in the pipes. Such simulations save a lot of time and can be performed. Energy losses due to friction due to shear stresses along pipe walls local losses that arises at pipe bends, valves, enlargements, contractions, etc 2 strength of pipe usually determined on basis of high and low pressures in conjunction with flow changes closing of valve or pump stop. Pdf evaluation of energy losses in pipes researchgate.
There are many types of losses of head for flowing liquids such as friction, inlet and outlet losses. Vazsonyi and andrew gardel and formulas obtained by assuming tjunction as combination of other pipe components. Definition dimensional analysis types darcy weisbech equation major losses minor losses causes head losses 3. Part of the energy losses are caused by the friction of the opening holes as fluid passing through them and the other part of energy losses are the result of the turbulence enhanced energy dissipation behind the porous structure. Estimating energy consumption and efficiency of mobile fluid. Minor losses in pipe flow are a major part in calculating the flow, pressure, or energy reduction in piping systems. Frost in the 1990s, as one of the updates to version 4. The second category called minor or singular head loss is due to the minor appurtenances and accessories present in a pipe network. A stopwatch to allow you to determine the flow rate of water. Jun 10, 2015 definition dimensional analysis types darcy weisbech equation major losses minor losses causes head losses 3. Entry length near the beginning of the pipe, the flow is not fully developed. Vazsonyi and andrew gardel and formulas obtained by assuming tjunction as combination of other pipe components and observations obtained from software experiments. Such losses are generally termed minor losses, with.
Integrated energy tool suite by us department of energy 2. Low flowrates through the test pipe can be generated using the head tank at the top of the support column. Introduction the problem of fluid flow in pipelines the prediction of flow rate through pipes of given characteristics, the calculation of energy conversions therein, and so forth is encountered in many areas of engineering practice. The flexible inlet tube on the test pipe is connected to the tapping at the base of the head tank and the inlet tube to the head tank is. This can fit to the losses in piping systems apparatus or be used by itself fitted to a wall and connected to a hydraulic bench. Eliminate sources of moisture prior to insulation replacement. Minimizing energy loss by optimizing pipe diameter and insulation thickness in steam distribution pipelines research pdf available may 2016 with 321. Pdf minimizing energy loss by optimizing pipe diameter. A model of inhome hot water distribution systems energy. Energy loss in pipes reynolds number fluid dynamics free 30. Insulate steam distribution and condensate return lines uninsulated steam distribution and condensate return lines are a constant source of wasted energy. In general, the smaller the size of pipe and fittings, the greater the losses. Energy losses in pipe flows are the result of friction between the fluid and the pipe walls and internal friction between fluid particles. One of the purposes of this study is also to study change in pressure loss with change in angle of tjunction.
Both circuits have common inlet and outlet pipes, controlled by valves. Various types of fittings, such as bends, couplings, tees, elbows, filters, strainers, etc. Liquid moving through pipes carries momentum and energy due to the forces acting upon it such as pressure and gravity. For the major losses, the volumetric flow rate was computed by using the equation. Major and minor losses in pipes and fittings john w llorens abstract. Damaged or wet insulation should be repaired or replaced immediately to avoid compromising the insulation value.
Pump system cheat sheet better buildings initiative. The nature of path through the valves and fittings determines the amount of energy losses. Guide for efficient hot water delivery system guide for efficient hot water delivery systems. Figure 5 shows the schematic layout of the pipe network to. The head loss in various pipe components, termed the minor loss and denoted hlminor. Friction head losses in straight pipes of different sizes can be investigated over a range of reynolds numbers from 103 to nearly 105, thereby covering the laminar. Friction losses are a complex function of the system geometry, the fluid properties and the flow rate in the system. Pdf energy losses in pipes used for the transportation of fluids water, petroleum etc. Energy savings from avoiding standby losses are calculated. Head energy of fluid weight head losses can be kinetic head potential head pressure head 6102015 4danial gondal head loss 4. The resistance to flow in a pipe network causes loss in the pressure head along the flow.
Energy losses in junctions is an important factor to be considered when designing sewer pipe network so that the system can store excess flow without flooding and overflows. Types, combustion in boilers, performances evaluation, analysis of losses, feed water treatment, blow down, energy conservation opportunities. Apparent losses represent a loss of revenue because the water is consumed but not accounted for and. Any change in a pipe in direction, in diameter, having a valve or other fitting will cause a loss of energy due to the disturbance in the flow.
Energy losses in pipes used for the transportation of fluids water, petroleum, gas, etc. The major and minor losses of pipes are computed for the technovate fluid circuit system and an edibon energy losses in bends module fme05. The thesis work first applied the state of art 1d dynamic model to examine quantitatively the uneven upstream water depth increase as well as the postconfluence energy loss. Minor losses the minor head losses which for some cases, such as short pipes with multiple fittings, are actually a large percentage of the total head loss hence, not really minor can be expressed as.
In short pipes, however, they ma y be greater than frictional losses and should be accounted for. The length of the pipe in addition to energy or head loss due to friction, there are always head losses in pipes due to an enlargement or contraction of the flow section, bends, junctions, and valves etc. Increase of velocity is associated with small head energy losses and decrease of velocity with large head losses. Associate professor, mechanical and materials engineering department portland state university, portland, oregon. Study of the head loss associated with a fluid flowing. Local losses usually result from abrupt changes in velocity leading t dd f ti hi h t t f th fl vvr145 vatten to eddy formation which extract energy from the mean flow. Minor loss coefficients for storm drain modeling with swmm william h. Wrap up energy savings with pipe insulation our easy pipe insulation program offers big rebates and fast paybacks. In addition to energy or head loss due to friction, there are always head losses in pipes due to an enlargement or contraction of the flow section, bends, junctions, and valves etc. Department of energys offi ce of energy effi ciency and renewable energy invests in a diverse portfolio of energy technologies. Turning off the recirculation pump not only saves pump energy use, but reduces heat loss from the bare pipes. In short pipes, however, they may be greater than frictional losses and should be accounted for.
A sourcebook for industry us department of energy 3. Energy losses in pipe flow major energy loss due to friction minor energy losses a. The list is organized by end use and building component and includes some water efficiency measures. Wrap up energy savings with pipe insulation avoid energy waste. Zigler national renewable energy laboratory nrel is a national laboratory of the u. Introduction pipe systems often include inlets, outlets, bends, and other pipe fittings in the. The f11o hydraulics bench which allows you to measure flow by timed volume collection. Includes pitot tube, venturi and orifice meters for flow measurement. Figure 5 shows the schematic layout of the pipe network to be. The purpose of the article is to detail the local heat losses in case of central heating systems. Flow through pipes 71 friction losses of head in pipes 72 secondary losses of head in pipes 73 flow through pipe systems 71 friction losses of head in pipes. Given the examples mentioned an effective estimate of 50% convective energy losses is a good first guess for calculation purposes in subslab situations with gravel as is prescribed in.
478 673 992 1343 658 162 886 832 1481 1570 1429 269 727 1499 293 1027 406 1098 583 126 34 1163 980 690 1572 829 1393 72 1351 348 1506 825 936 1421 921 366 551 338 927