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# Heat Exchangers - Science topic

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Questions related to Heat Exchangers

I am student and I want to know about the best heat exchanger

It's a tube & shell exchanger

Consider a heat exchanger with two streams A & B. Going by Fuel-Product definition for exergy analysis, suppose stream A is the fuel stream and stream B is the product stream. My question is whether the following can be possible.

Exergy @ A_in > Exergy @ A_out &

Exergy @ B_in > Exergy @ B_out.

If this will be true then Exergy destruction = Exergy of Fuel - Exergy of Product will become more than exergy of fuel and thus make the exergetic efficiency of that heat exchanger to be negative.

The difference air heat exchanger and water heat exchangers

The terms of type of used pipe

For a regular Low Temperature Striling Engine, how much mechanical energy can I produce by using hot water at around 350K?

I want to calculate

**Rayleigh number**and**Nusselt number**of a**PCM-heatsink**to analyze the intensity of the**natural convection of PCM**. There are some**fins**inside my heatsink to enhance the heat transfer. Now I am having trouble calculating the**characteristic length**to use in Rayleigh and Nusselt dimensionless numbers.I would be grateful if you could help me.

Hi friends, i am doing simulation on heat exchanger. when i am trying with Coupled algorithm, solution is easily converged. but when i am changing to PISO, iteration run for 24 iteratio(within 1min), after that no response. more than 30 min. no error like thing come. (simply as in attached file. why this occur? what to do?

I am working on modeling and optimization of evaporator and condenser, both are plate type heat exchanger. The primary fluid is refrigerant mixture (zeotropic) and secondary fluid is hot water. For water, the open literature has numerous heat transfer correlations but for refrigerant mixtures I could not find any flow boiling or condensation correlation in heat exchangers. Although there are few studies that provide flow boiling or condensation correlation of zeotropic fluids in tube. But since the flow pattern is different in tube and plate heat exchanger (vortex or swirl flow), is it reasonable to use flow boiling or condensation correlation of zeotropic fluids in tube instead for flow in plate heat exchanger as well?

The flow boiling and condensation heat transfer correlation for refrigerant mixtures in tube wi

I need two model heat exhanger between air and water. But air will be admitted in liquid state at negative temperature and on leaving the heat exchanger it should be in gaseous state.

In this problem two fluids are involved

Water

Air

Once again Air has enter in

Liquid state

On transferring heat from water it has to be converted to

Vapour.

I'm aware interphasechangefoam for phase change and CHTMultiregionfoam for two fluids. But in this case two fluids are involved. In this two fluid, one fluid has to undergo phase change.

Regards

Dr. Ijaz Fazil.

Suppose we have

**a HEN with several multi-pass heat exchangers**. However, due to some technical constraints**all these exchangers are modelled simply using single pass equations.**What will the impact if such a simplistic model is used in optimization problems, such as

**network optimization for retrofitting or cleaning scheduling?**For instance, it is clear that we may not end up with global optimal solutions but still what will the qualitative impact of such approximations?

The open literatures provide lots of correlation for estimating the in-tube CO2 flow boiling heat transfer coefficient. In the case of plate heat exchanger, the correlations are available for R134a, R410A, etc. I was looking for something generalized or specific correlation that accounts the phase change (boiling/evaporation) for CO2 inside a brazed plate heat exchanger (BPHX). Because, the flow inside a BPHX should be very different than the in-tube flow.

Do

**obstacles**in a channel change the regime from**laminar**to**turbulent**while the**Reynolds number is under 2300**(approximately 1000)?Please introduce related studies.

May below article will help u,

**Counter current heat exchanger**

Hello everyone,

I would like to simulate a heat exchanger with tear stream in aspen plus. I got convergence in shortcut mode. But when I change it into the rigorous mode, I no longer can get the convergence. I tried the following ideas to get the convergence but no luck in getting it.

1) Changed the method

2) Relaxed tolerance

3) Initialized the stream

Any idea to solve the problem will be appreciated.

Thank you in advance

Regards,

Kamalidevi

I am trying to size a radiator for a car. Is there is a specific software used by automobile engineers for sizing the radiator? Can I use Aspen EDR for compact heat exchangers?

How to measure thermal conductivity of Fins in heat sink or heat exchanger.

I have calculated the power losses of the system and the inlet and outlet temperatures for both air and waterside. Using LMTD method, the overall heat transfer coefficient of the CHE was found.

I am unable to proceed further, mainly because I could not find any reports on the heat exchanger(it is similar to a car radiator but smaller form factor) I am working with. How do I find the heat transfer coefficient for the air and water side?

I am unsure of which relations to use from Kays and London book on Compact Heat exchangers (CHE).

Any suggestion on software/books/reports on finding the heat transfer coefficient of this type of heat exchanger would be greatly helpful.

Thanking you in advance.

In my car radiator, the coolant leaking due to minor crack in the plastic. The crack is in the initial stage so no problem now. But coolant leak by drop by drop.

I like to fill the crack in the plastic. What type of glue is used to fill the crack in plastic?

Normal car uses Radiatior system to cool down the engine system. But in Electric vehicle that there is no nead of radiators i think.

Someboby told me electric vehicles using heatsink. Please clarify what type of heatsink is used and how heat in Electric vehicle is controlled.

It must have high thermal conductivity even if it is not electrically conductive. However, it should had high stiffness value so that it will not warping

I need a test bench of a heat exchanger to do experiments on the theme 'fouling of heat exchangers.'

Hello everybody,

i hope you're doing well,

please could you help me the question above using numerical calculations

We are currently looking for gas-to-liquid heat exchanger for the reduction of high temperature gas to low temperature gas. Which type of Heat Exchanger would you suggest to reduce temp of 200 degree C to 30-40 degree C.

I would like to model a heat exchanger by two heaters on aspen.

But the problem is that by transferring the flow from the hot side to the cold side, I end up with a final temperature of the cold fluid higher than that of the hot fluid of departure

If given inlet gas temperature is 25 degree celcius and outlet gas temperature 220 degree celcius

Hi, I need to calculate the insulation system of a plant of rice bran oil extraction that is consist of pipes, heat exchanger, flash, valve, and pump. Is there any formula to suggest? I read some handbooks, but I could not calculate them for the whole system.

I want to write my thesis for master course and i need some suggestions to increase the efficiency of plate heat exchanger.

Doing exergy analysis of steam turbine. However, the exergy balance on boiler (heat exchanger) includes exergy of fuel which is to be determined. The measured data contained the mass flow rate of fuel.

I am creating a heat exchanger for the lattice structure core on ntopology to be transferred to Ansys for simulation afterwards. But the meshing is faulty and Ansys cannot process it correctly. Is there any way to fix the intersecting and other types of meshing errors on ntopology? Is there any way to save the ntop filesbefore meshing?

Thanks

Hossein

Any recommendations on books would be really helpful.

I'm a Mechanical Engineering student fin heat exchanges. I would like to the know the best material for make fin. But because of lack of knowledge on the subject, I'm confused about where to start my design. hopefully someone who knowledgeable in heat transfer field can answer my question. thank you.

There are multiple methods to calculate cold and hot outlet temperatures, e.g.

**LMTD**and**P-NTU.****P-NTU**directly calculates both the hot and cold outlet temperatures using two linear equations based on (a) exchangers geometry (b) flow and (c) heat-capacity of the fluids.**LMTD**based method requires (a) exchangers geometry (b) flow (c) heat-capacity of the fluids and (d) one of the outlet temperatures to calculate the remaining outlet temperature.

(Note : LMTD method can find both the outlet temperatures, if heat exchanger is single-pass)

Both the methods give same answers (while designing and rating heat exchangers) !

My question is as follows:

**Is recursive type calculations in LMTD can be considered as a drawback of LMTD method? , Particularly in heat exchanger networks?**

can we design heat exchanger network HEN with only 1 stream on above pinch? Is it possible?

I've been working on the heat exchanger design for fermentation systems, and found an explanation in the literature on how to calculate the cooling-coil length. However, I haven't found information on the volume or area that a cooling coil should occupy in a fermenter yet.

The formulas for the shell and tube heat exchanger can't exactly be used for this since the coolers/heaters only have 1 inlet and 1 outlet, unlike heat exchangers that have tube inlet & outlet, as well as shell inlet and outlet. Also, there is no heat transfer coefficient for coolers/heaters unlike heat exchangers.

What other parameters can I compute? Can I ask for formulas that I can use for the specification sheet I'm making for coolers and heaters?

Thank you so much!

I am using k-epsilon turbulent model for heat exchanger design and i am facing this error consistently.

what i have done so far to try to solve this error is:

a) run the stationary model that converged and is in agreement with our experimental data

b) Then i used the solution of stationary model to run the transient model but finding this error every time.

If any one of you knows how to resolve this error kindly give your suggestions.

Hello,

I am trying to simulate a simple heat exchanger which has a laminar flow of water inside the single slab channel and a phase change material stored underneath. The heat exchanger has one row of fins on the slab with air between the fins. The photo of the heat exchanger is attached.

While I run the transient simulation, the time steps of the transient solver are extremely low resulting in a very long runtime. As seen in the convergence graph, the Reciprocal of Time Step Sizes are extremely high and after 175 time steps, the simulation has reached only 0.0711 seconds. The simulation was running for over a day. This is while a simple heat transfer simulation without adopting the phase change material is not so time-consuming.

Is there any way to improve the timing or is COMSOl generally so slow on phase change material modeling?

Greetings !

respected dear i am working to a novel design of wet cooling tower for my final year project as B.E requirement.

I am confused about that if i use cars radiator instate of air to Air tube heat exchanger at the top of the tower ?

kindly help me and guide me , what will be results if i use car's radiator instate of air to air tube heat exchanger ? it would increase the efficiency of wet cooling tower or may decrease ?

I am now modelling shell and tube heat exchanger using COMSOL Multiphysics 5.3a.

I have several questions:

1. What is the benefit of modelling these equipments in finite element software, in terms of safety?

2. Does this FEM software really helpful on consultant engineer in designing the equipment. If yes, in what way? If not, why?

3. Do FEM software really credible and powerful? Many of the journal state that the error obtained ~15%, but ain't this software too good to be true?

4. One with skills using FEM software, is it in demand?

Thank you for answering!

Hello everyone,

I am working on a heat transfer and pressure drop study on a heat exchanger.I need to measure the inlet and exit temperatures as well as the wall temperatures at different locations along the exchanger length.For wall temperature,I am attaching thermocouples on the wall .However ,I am facing a problem how to accurately measure the Inlet and Exit temperatures of Fluid streams.Anyone working on the same area can help me .Thanks in advance

As a part of my thesis I am designing Finned pack heat exchangers for cooling/condensing warm air with water. I am not getting the exact procedure for it. I am reffering multiple research papers but all seem to have different information. Does anyone know of a relevant literature where I can find the process.

The exact type of heat exchanger I want to design : http://www.deltacoils.it/?locale=it_IT

Actually my part is to check the efficiency of the preinstalled heat exchanger I thought by designing the heat exchanger I would get a better under the efficiency is this approach correct also please suggest as per your experience.

This is my industry production problem. In the air conditioner heat exchanger coil bending process, There must be a polyester film between the 2 layers of heat exchanger coil for preventing deformation of aluminum fin plate. It's inserted by a man and be removed by a man.

I'm thinking to make a foolproof system for a forgetting remove this film but can't figure out what kind of sensor would suitable for this situation. Could anyone here suggest any product or method for this situation ?

In your opinion, which cooling technology is the best option to support the increasing demand for heat removal in modern engineering designs used in aircraft systems?

I want to simulate the phase change through out the heat exchanger that may be used in refinery by fluent. The point where the phase of oil will change is very important in this type of stations ,how I can find it or indicated using fluent.

As a part of my system, there is a heat exchanger.

Hot stream - water vapour - comes in at 17.12degC, 0,00714648 bar, completely in the vapour phase

Cold stream - refrigerant R1234ze in a saturated liquid state. The properties of HEATX is given below in the image. I get this error - ** ERROR T-LOOP NOT CONVERGED IN 37 ITERATIONS. FLASH FAILED FOR HOT STREAM DURING ENERGY BALANCE CALCULATION

I would be grateful if someone could clarify what this error could be due to. Thank you.

What is the best and easy to realize method to heat hydrogen / carbon dioxide mixture at10 bar to 320degC? My first idea is to use a thermostat with circulating thermal fluid at 350degC and a plate heat exchanger. But I can not find a heat exchanger with hydrogen resistance and such temperature / pressure spec. The mass flow is about 20 kg/h.

Hello, I am tasked with designing a heat exchanger for pasteurizing beer. I am currently using the Log Mean Temperature Difference LMTD method to do the thermal analysis. I am struggling to find the temperature that beer would often be at before entering a shell and tube heat exchanger for pasteurization and the temperature that the heating water would be at when entering the heat exchanger. The heat exchanger is meant to handle a maximum mass flow rate of 14kg/s if that information is of any help.

Dear all,

Would you please help me to find out the best approach to calculate the potential heat recovery from exothermic reactions? Are there any good references to introduce me in order to enhance my knowledge over recovering heat from exothermic reactions. I will be very thankful for your helpful advice and recommendations.

Thanks in Advance for your kind considerations.

Yours faithfully,

Nashmin

I want to determine the Nusselt number (Nu=hD

_{h}/k) in the heat exchanger. In calculate of heat transfer coefficient (h=q''/(T_{w}-T_{b})), for the q'' parameter, I use the total heat flux of the channel walls that is the contact with the fluid and use the average temperature of these walls for the T_{w}parameter. In this equation, I need the bulk temperature (T_{b}). How can I calculate it in Comsol multiphysics?I am analyzing two adjacent interconnected rectangular channel flow patterns. The image of my numerical model is attached below.

The fluent solver was pressure based, and velocity formation was absolute. The SIMPLE algorithm was used. Laminar regime was selected and energy equation was kept on. Boundary conditions were checked carefully. Inlet velocity and pressure outlet conditions were applied. Uniform Heat flux was applied at the bottom face. Solid fluid interfaces are thermally coupled. Second order upwind equations were used for energy and momentum equations. The residuals were kept 10^−5 range, and the solution was fully converged.

I have drawn a centerline inside a mini-channel for observing velocity distribution. Is my solution right? and velocity profile having zigzag is okay? if not, pls explain.

I have double pipe heat exchanger and I want to calculate numerically the local temperature reference that used for calculation heat transfer coefficient locally .If the heat flux is constant are known and all properties is known too.I want to compare with experimental work .The temperature will change as mesh change and cannot be used for comparison with experimental work . This mean can not be calculated where Tref=f(y).

you know h=q/(Tw-Tref) where q heat flux.

must I calculate h or Tref manually with another assumptions?

Stoitchkov and Dimitrov produced a short-cut method for the measurement of heat exchangers for wet surface crossflow plate quality. This involves a correction to the effectiveness determined in compliance with the Maclaine-cross and Banks procedure. For this reason, a new model has been developed with a moving water film, referring to the real conditions in these heat exchangers.

Reference.

N. Stoitchkov and G. J. I. j. o. r. Dimitrov, "Effectiveness of crossflow plate heat exchanger for indirect evaporative cooling: Efficacité des échangeurs thermiques à plaques, à courants croises pour refroidissement indirect évaporatif," vol. 21, pp. 463-471, 1998.

Solution to dissolve phosphogysum in heat exchanger of SS-316 moc.

Hi everyone

I am working on a shell and helically coiled tube heat exchanger with laminar flow through the shell and turbulent flow through the coil tube. I have performed iterations for coil by selecting different types of turbulence models but in each case, energy starts to diverge after some iterations (images attached).

What is the possible reason for this?

Dear all,

e-NTU equation can be written as follows:

e = {1-exp[-NTU(1-CR)]} / {1-CR*exp[-NTU(1-CR)]};

To simplify above, we can write it as follows:

e = 1-exp[C*(1-X)] / 1-X*exp[C*(1-X)]

Can we linearize e , given that X is a variable in both the numerator and denominator?

I want to analyse the impact of heat exchange mechanisms in a fluid contained in a box under different pressure levels using Star-CCM+.

The Navier-Stokes solver fails when the pressure is low enough to produce KN>>1, under free molecular flow regime. I think this can be achieved by defining the physics continuum by selecting a User Defined EOS.

I just wanted to know if this has been attempted or maybe a different method is better.

Please see attached formed plate to be used as base of heat transfer area in a heat exchanger?

I am designing a heat exchanger and I set the shell diameter, tube diameter, and shell length as input parameters to perform an optimisation analysis. The output parameters I set are the temperatures at the outlets and the effectiveness of the heat exchanger.

The temperature at the inlet of the shell is 85C, and at the inlet of the tube is 15C.

When update the DoE for the response surface, I am getting unreasonable results for the temperatures at the outlets (some are greater than 100C).

I want to know why this is happening and if there is a way to fix it..

If i delete the unrealistic design points, would I still be able to generate the response surface? Or should I find the source of the problem and run the DoE again?

Fouling or scaling is becoming a major hurdle for getting high heat transfer exchange between two fluids. Scaling is formed in tubes and the type of scale formation is difficult to assess since it has a combination of several impurities. Thermal resistance of scale formation is taken for the type of fluid flowing in a heat exchanger to estimate the practical heat transfer. In order to prevent fouling or scale formation what are the precautions and remedies to be taken?

I am designing an isothermal multitubular reactor and have sized and completed the tubular design. the tubular volume required and the outer surface area of the tubes has been defined (9000 tubes an outer surface area of 14,000m^2). the heat needed to be removed has also been defined and is 9 MW. How would i calculate the temperature rise on the shell side of the heat exchanger. would the formula Q=UATlm still apply and if so how could I solve Tlm for the temperature rise on the shell side.

I am working on a shell and helically coil tube heat exchanger as shown. The flow through the shell is laminar and through the coil is turbulent. Which model should I select from Fluent to solve this problem. Is it possible to differentiate the laminar and turbulent regions in fluent and then applying the models?

I did a pretty simple simulation of an exothermic reaction using RPlug in Aspen plus. Initially the feed was heated using a heater block. Since the reaction is exothermic, I tried to use the reactor product stream to heat the reactor feed using heat exchanger block in aspen plus. After replacing the heater with heat exchanger, the simulation converged fairly easily, at first. But once I purge the simulation results, I cannot get the simulation converged again. Any idea how can I get the simulation converged after purging the results.??

I just need a validation equation or a research with a similar heat exchanger feature such as an air-to-air Hx

Most of the literature on shell and tube heat exchangers presenting the heat transfer coefficient correlations does not specify if there are any differences when dealing with vertical and horizontal orientations. Would the differences be only in terms of the shell-side fluid velocity ( and consequently Re) but the correlations would remain the same? How do these differences in orientation play out in the design?

If the entrance and exit teperatures of a fluid which is flowing through a heat exchanger is known, how could i plot the cooling curve of the fluid along the tube?

The overall heat coefficient, mass flow rate and the diameter of the tube are also known.

I was reading this research paper titled ' A Fully Wet and Fully Dry Tiny Circular Fin Method for Heat and Mass Transfer Characteristics for Plain Fin-and-Tube Heat Exchangers Under Dehumidifying Conditions ', and tried to implement the algorithm mentioned in it for wet heat exchangers. But, I could not find any data related to outlet air enthalpy and outlet water temperature to calculate the Qavg as mentioned in the first step of the algorithm. Can anyone tell me where I can find that data?

Should I mesh the solid domain ? or should I use wall thickness? or Shell conduction? for Heat Transfer between two fluids of a Heat Exchanger.

what is recommended?

I want to cool Natural Gas from 195 Kelvin to 138 Klevin in a heat exchanger by using liquid nitrogen as the coolant medium. When entering the heat exchanger, the liquid nitrogen will have a pressure of 10 bar and temperature of 80 Kelvin. I need to find the necessary lenght of the heat exchanger. For this purpose i need to know the overall heat transfer coefficient of liquid nitrogen. I would be very glad if you could advise me where to find this value. I would also be glad if you could advise me other coolants in order to cool natural gas to 138 Kelvin.

Hi Guys. I'm a mechanical engineer and have a bit trouble, would be very glad if you could help me with my questions.

I have a pressurized tank which contains Natural Gas at 200 Bar and 293 Kelvin. This tank is directly connected to a heat exchanger and in that device, the gas must be cooled to 150 Kelvin and will be stored as LNG at 20 Bar. I have to determine the necessary tube dimensions of the heat exchanger (Radius and Lenght) but I'm a bit confused since I dont have any informations about the flow velocity nor the flow rate. I need an idea how I could determine the flow rate of the gas. If i select the tube diameter randomly, what would be the flow rate of the gas at the exit of the pressurized tank?

How to find the air side pressure drop in a spiral fin cross flow heat exchanger?

The pressure difference at the inlet and outlet is very low compared to the experimental results, which I calculated according to the average pressure.

When I take the difference of the maximum and minimum pressures, the pressure drop comes closer to the experimental results.

Does anyone have an idea for cfd analysis in Comsol program for this situation?

thanks for your help in advance

Basically, it's a cylindrical tube of steel with inlet temperature of milk at

**4 degrees Celsius**and the outlet temperature would be**72 degrees Celsius**. The mass flow rate is**1 Kg/s**while the**length**and**diameter**of the tube are to be chosen, and the heat energy requirement to fulfill the above conditions is to be found.**Can someone guide me how to proceed**. What is the relationship to be used, which would include these parameters, length and diameter of the Tube and the uniform heat energy supplied to the tube to make the temperature reach 72 degrees at the outlet, from the 4 degrees inlet temperature?

I need to design an spiral heat exchanger, buy I don't know what reference or bibliography (preferably a book) should I consult in order to get an updated and reliable methodology related with this topic.