What is Mass flow: Definition and 132 Discussions

Mass flow, also known as “mass transfer” and “bulk flow”, is the movement of fluids down a pressure or temperature gradient, particularly in the life sciences. As such, mass flow is a subject of study in both fluid dynamics and biology. Examples of mass flow include blood circulation and transport of water in vascular plant tissues. Mass flow is not to be confused with diffusion which depends on concentration gradients within a medium rather than pressure gradients of the medium itself.

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1. Maximum mass flow in a shell & tube heat exchanger

I’ve been trying to understand what’s the maximum mass flow that can be used in a already existing shell&tube heat exchanger. The only information i have available is the datasheet of the heat exchanger above mentioned and the fact that we want to increase the hot fluid flow from 30 ton/h to 40...
2. Determining Reverse Mass Flow Rate Formula for Multiple Diameter Tubes

Alright, this is more of a conceptual question than a HW question that will nonetheless help me design something. In the attached image, air is flowing through a large area tube and then a small area tube from right to left. A collaborator previously figured out the equation for measuring the...
3. Engineering Mass flow rate as a function of time

At first, I inputted h(t), of which I solved for, into the mass flow rate formula. So it looked something like this, m-dot(t) = -(density)*[sqrt(g*(H-(g*d^4*t^2/D^4)]*(pi/4)*d^2 But I don't think that's right? Any thoughts?
4. Coolant Mass Flow Rate Through Subchannel in Nuclear Fuel Assembly

I am trying to find the mass flow rate of coolant through a channel within a hexagonal nuclear fuel assembly. I am given the specific heat of the fluid, the coolant inlet and outlet temperatures, the total power produced by a single fuel pin, the diameter of the fuel pin, the length of the fuel...
5. Engineering Thermodynamics, Calculating the required mass flow

I have solved this question and it seemed pretty easy, but I got an extremely large number for the mass flow, I had to post the question here to make sure I did it correctly. Any help will be appreciated.
6. I General guidelines on the physics of flows at junctions?

Let's start with a configuration in which one tube, A, splits into two, B and C. We can write the relationship $$A_A v_A = A_B v_B + A_C v_C$$ When I first saw this formula (which was very recently), I wanted to solve for ##v_B## and ##v_C## given all other values. I can't of course. There are...
7. Discontinuity of velocity in a problem on mass flow and momentum

In this question, the particles are constantly transmitting their momentum to the rocket. The force required to keep the rocket stable can be express as ##\vec F=(\vec v-\vec u)\dot m##. However, when I tried to solve this question using the Newton's 2nd law, I found that the infinitesimal...
8. Calculate the air pressure needed for a projectile to travel X distance

Hello! I'm brand new to the physics forum so please excuse any mistakes I make. I'm not even sure if I'm in the right forum section lol. My goal is to create a air cannon to launch a piece of dog food (super overkill) and I have pretty much 0 background in anything post-high school physics. I'm...
9. Refrigerant - mass flow, power, COP

This is a past exam Q, I don't have the attached pressure enthalpy diagram. Q = 120kW Cp = Refrigerant enthalpy = I've looked this up, for ammonia enthalpy = 35.06 kJ / mol T2 = 5 degrees C = (5 deg C) (1100 kPa/300 kPa) = 18.33 deg C +273.15 K = 291.48 K T1 = 2 degrees C = (2 deg C)(1100...
10. Calculating the Mass Flow Rate of a boiler

Im trying to do some past exam papers. If i can get help with the method on how to solve and have correct formulas, it will help me. I) There is one formula in the notes to get mass flow rate: Heat lost by steam = Heat taken up by water GsHfg = (GwCpw)(change in temp) Gs x 2748 x 10x103 =...
11. Convert Mass Flow Rate to Molar Flow Rate

how can i convert mass flow rate into molar flow rate using density of the gas.
12. Finding the average water mass flow rate in a water rocket

Could anyone kindly kind me as to where this formula is derived from and how, because I searched and can't find it anywhere
13. How is mass flow rate a force?

Lets say if I have a pipe with one end closed, and drill a small hole on the side of the pipe near the closed end. Then I use vacuum at the open end to create mass flow exiting the pipe. Where is the opposite force on the pipe? [crackpot youtube video deleted by moderator @russ_watters ]
14. Automotive Can the mass flow rate change?

Hello everyone, Can the mass flow rate of air by a propeller connected to an engine through a small tube change if the rpm of the propeller is increased?
15. Fuel cell mass flow rate magnitudes

Hello, Can you tell me please the mass flow rate of hydrogen and oxygen per unit of area of electrodes in fuel cells? Or if you have information on the mass flow rate of hydrogen and air per volume of fuel cell stack? I understand this may vary, but I am looking for publications or other...
16. Deriving the Equation for Average Water Mass Flow Rate in Water Rocket Launches

Hey, I'm a student who has to complete a written assignment for physics. I chose to launch water rockets and investigate the effect of volume on the range. I am trying to also come up with a mathematical model however I am struggling to understand an equation I found the following equation to...
17. I Calculating Robert Zubrin's Dipole Drive Mass Flow

I'm trying to understand calculation made Robert Zubrin in his presentation on Dipole Drive source: In here he made the following statement "A Coulomb of protons has a mass of 0.011 milligrams. If the jet power is 400 W, and the potential difference is 64 V, so the proton current will be...
18. How to calculate Fuel Mass Flow Rate

I'm having a brain storm, If I have an 8 cylinder 4 stroke engine running at 4000 rpm over a 10 minute test and it consumes 4.4 Kg of fuel, then is the fuel mass flow rate as simple as the 4.4 Kg divided by the time to give me an answer on Kg/sec ? Thanks,
19. How is mass flow an inexact differential

How is mass flow rate within an annular region of a pipe taken to be an inexact differential? I read it in Fluid Mechanics textbook by Yunus A. Cengel and John M. Cimbala. The mass flow rate through the annulus is given to be inexact differential. Why is mass flow through the annulus not equal...
20. Heat Transfer and mass flow rate

Hi, wondered if anyone can give me a pointer on this problem I am working on. 6 Diesel engines each with power 55kW running, given output cooling water temperature of 80°C, and required return temp of 60°C. The coolant is to be fed through a heat exchanger, with the heat exchanger outlet to be...
21. Mass flow rate calculation from velocity contour in pipe

Hello all, Looking for ideas on how to calculate mass flow rate from a velocity contour plot. The cross-sectional area is circular. An example of the velocity contour plot is shown in the figure below: In most of the cases (as exemplified above) the flow is non-axisymmetric. Any suggestions...
22. Understanding Backpressure Effects on Flow Meter Calibration

Hello all, I have an in-house designed flow meter with roughly the configuration in the figure. In the setup, a restriction is placed in the flow stream (the rows of horizontal lines in the figure). Pressure measurements upstream and downstream of the restriction, P1 and P2, respectively are...
23. K

How to calculate : Mass flow of water vapor in the air (kg/h)

Hello Homework Statement Lets say i have the given parameters: air volume flow : V = 36 m3/h Relative humidity: RH=33% air mixing ratio : X = 5.5 (1g H2O) / 1kg (DRY AIR) (calculated from RH) air temperature : T= 20 C So i know how much mass of water is the air compared to the air's "dry air"...
24. T

Relationship between the pressure gradient and mass flow of a gas

Hi everyone, I would like to know how to calculate the diameter of a pipe when we know the desired mass flow, the gas type, and the pressure at both end. I have these requirements : Gas : O2 Molecular weight : 0.032 [kg / mol] Desired mass flow : 0.32 [kg / s] Pressure in the gas tank : p1 =...
25. How mass flow and pressure ratio is related in case of a Gas Turbine

Hi, As per my observation and experience, when we use evaporative cooler to cool the inlet air to the gas turbine, the compressor discharge pressure (i.e PCD or P3) rises. As, the temp. of the inlet air drops and the mass flow increases due to the increase in density, I believe the discharge...
26. Mass Flow Rate of Flue Gas in Sugar Industry

Hello, I want to find the mass flow rate of flue gas, i have only the diameter of pipe and ID fan speed which are 1.48Meter and 980 RPM respectively
27. Not sure Exactly what Pressure I am Solving for in this Form

Hello all, I am posting this question here in this thread and not the homework thread since it is not a homework problem but something I have been working on myself. Let us imagine a fluid flowing through a pipe, we can measure pipe diameter and fluid velocity. The density of the fluid is also...
28. Strange unit of mass flow rate G?

Hi When I was writting my thesis I found in an article, published in International Journal of Heat and Mass Transfer, an unit of mass flow rate G - kg/(m^2*s). Isn´t it wrong? I think that the unit of mass flow rate is kg/s. Would you mind helping me to figure it out? Thanks.
29. Calculating Mass Flow Rate of Steam

Homework Statement If 5% of the heat available for steam production is lost to the atmosphere, determine the amount of steam raised per hour when the total flow of flue gases is 1400 kmol h-1. qmH = 1400 kmol h-1 Flue gas temperatures: Inlet = 1832°C Outlet = 300°C Water temperature: Inlet...
30. I Mass Flow Rate Problem: Easy Unite Conversion Tricks

Hi, I am not science student. Can anyone help me to solve this? Density and velocity of a fluid is given as 920kg/m3 and 5m/s, this fluid is flowing through an area of 25cm2. Calculate the mass flow rate? I am in search of some easy unite conversion tricks also.
31. Convert Volumetric Flow Rate to Mass Flow Rate: A Guide

How to convert volumetric flow rate to mass flow rate?
32. Mass Flow Rate of Pressure Regulator

Hey, I have an air tank that is at a set pressure, say 3000psi, and I have attached a regulator to the end that regulates the pressure down to 800psi. As the valve on the tank is opened the pressure and the mass in the container will decrease. If there was no regulator the mass flow rate would...
33. Mass flow rate through a regulator

Hi, We have a canister at a set pressure (4500psi) full of compressed air. A single stage pressure regulator is fitted to the canister that reduces the outlet pressure to 850psi. The flow from the regulator is then used in a divergent nozzle to create a thrust force capable of lifting a small...
34. Solving Mass Flow Problem Homework

Homework Statement A sand-spraying locomotive sprays sand horizontally into a freight car. The locomotive and the freight car are not attached. The engineer in the locomotive maintains his speed so that the distance to the freight car is constant. The sand is transferred at a rate...
35. Derivative in mass flow rate equation - Hydrology

Hello, I am working with the mass flow rate equation which is:$$\frac{d \dot{m}}{dt}=\dot{m}_{in}-\dot{m}_{out}$$ To determine the change of the height of water in a reservoir. Assuming m_in = 10 and m_out = sqrt(20h), then : \frac{d (\rho \cdot Q) }{dt}=\rho \cdot Q_{in} - \rho\cdot...
36. I Pressurization rate vs. Mass Flow rate

Good afternoon all, I am doing some back of napkin calcs for work and am having trouble finding an answer (or one that I can understand--its been a while since undergrad). We have a valve that has particular flow rate requirements to prevent unseating the valve seal. This is a mass flow rate...
37. Calculating mass flow rate while assuming shock losses

Below is a 2 part question regarding gravitational pipe flow, I have managed to do Q1) and have got an answer of 144 kg/s. However Q2 asks that shock losses be considered, Although I know how to calculate the shock pressure loss I am unsure of how to apply this to my calculation to get a new...
38. Calculation of mass flow rate of 50MW

Hi i have calculated compressor , combustor , turbine inlet and outlet temperature , pressure so on and my output of gas turbine is 50MW , So for this i want to calculate the mass flow rate of air and fuel in compressor , combustor , turbine . Like m0=?,m1=?fan inlet,m2=? compressor inlet,m3=...
39. I Energy needed for achieving this mass flow rate for a rocket

Hey, Suppose you have an enclosed vessel that is full of water. You heat it up then you open a valve, and that will create enough thrust for it to act as a rocket. How much energy is needed for a steam rocket to get heated enough to achieve a mass flow rate of 2430 Kg/s. Mass of water= 256...
40. Automotive Temperature and mass flow rate of ICE exhaust gas

Hi everyone I searched about the mass flow rates and temperatures of exhaust gases of light gasoline internal combustion engine at different condition but I don't fond anything yet . Anyone can guide me? .
41. Stator inlet angle in turbomachine?

Hello, I am wondering about the following action in a stator: If the inlet angle in a stator is B, and the outlet angle is -B, what exactly is happening? Axial vlocity should be constant, and so should the relative velocities except being mirrored and i am asuming infinitely thin blades.. Can...
42. High school project -- Finding mass flow rate, air velocity

Hi, First-timer here! I'm designing a physics project that involves pumping a certain pressure of air into an empty bottle. SETUP: The bottom of the bottle has a small hole through which a thumb tack fits tightly; the top (cap-side) has a valve through which the air is inserted. The bottle is...
43. Help with mass flow rate of turbine?

Homework Statement An turbine expands air at 1300 kPa and 500oC to 100 kPa and 127oC. Air enters the turbine through a 0.2-m2 opening with an average velocity of 50 m/s, and exhausts through a 1-m2 opening. Determine (a) the mass flow rate of air through the turbine Homework Equations PV=RT m...
44. Turbocharger: Mass flow rate and pressure ratio

Hello everyone, i am currently dimensioning a compression system using a vehicle turbocharger and need to find a way to relate the pressure ratio of the compressor and the mass flow rate. (flows trough compressor and turbine are of course separated) For the turbine, one can use Stodola's...
45. Reduce mass flow rate may increase air velocity?

Hi, I used a blower to flow air across an open duct through a nozzle. By using a gate valve, the mass flow rates were controlled. I took measurement in 3 different locations along the ducts. But, why by decreasing the mass flow rate, the air velocity was increased? It is just happened for the...
46. Calculate Remaining Anesthetic Time: Mass Flow Rate Question

Homework Statement A patient, on an anesthetic, is hooked up with only 18 mg of the anesthetic remaining. If the current flow is 12 mg/h and the dentist needs to increase the flow to 20.0 mg/h within two minutes, then how long will it take for the anesthetic to run out? Homework Equations...
47. Can force be expressed as mass flow rate times velocity

I know that F=ma which give the units of kg.m/s/s (in SI units) but can force also be expressed as mass flow rate times velocity which also has the same units? Example: water coming out a hose or gas coming out a spray can?
48. Can you calculate liquid mass flow based on inlet and outlet pressure?

Hello, Can anyone answer me how to caluculate the massflow of the liquid. I know the inlet mass flow , volume of the pipe , and the inlet pressure and outlet pressure of the pipe. Do we have any equation to caluculate the outletmass flow with respect to differential pressure? Can anyone help...
49. Have mass flow rate, want superficial vapour velocity

Hi guys, quick simple question. Lets say I have a pipe separated into 3 sectoins (all horizontal), all have the same flow areas. In the first section it is all liquid water. I know the mass flow rate in this. In the second section the water is heated. And I can work out the steam quality...
50. Mass Flow of Snow while Plowing?

Homework Statement Let's say I am plowing snow in a straight line using a standard V-plow. The angle of the V between both blades is 130 degrees. The coefficient of kinetic friction between the blades and the snow is about .1. The speed of the plow is 5 mph or 2.2 meters per second. The...