Questions tagged [heat-exchanger]

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Is it possible to do hot gas filtration through fluidized bed reactors

I am working on flue gas filtration and HCl gas is to be removed from the gas. I am wondering if a fluidized bed reactor could be used to filter the gas. The problem is, a furnace is used to provide ...
2 votes
2 answers
55 views

Does it make sense to increase the thermal "dead weight" of a wood stove?

It is general practice to put a bucket of water on top of a wood stove to keep air humidity under control during the burning of the stove. But, such a bucket is also bound to keep some more thermal ...
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Heat Transfer in a tubular reactor with constant jacket temperature - impossible solution?

I have received from my professor the following problem: A first-order exothermic reaction A -> B takes place in a tubular reactor (typical PFR). The tube is cooled to a constant wall temperature $...
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1 answer
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Method for computing the pressure drop across a bank of tubes

I would like to determine the pressure drop of fluid in cross flow over a bank of tubes. (see figure 1). Previously, I've used the correlation listed in "Fundamentals of Heat and Mass Transfer&...
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1 answer
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Predicting the behaviour of a boiler system if we modify temperatures

I am currently studying a boiler without many technical data. Below a short description: Fuel is put inside the boiler furnace. Primary (F1) and secondary air (F2) fans allow fresh air to go through ...
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4 votes
2 answers
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Cooling system to maintain 0.5 °C at 95% humidity

I am looking for some guidance on a redneck cooling system. I need to store seeding trees at a temperature just above freezing, and at a humidity of close to saturation. I only need the system for ...
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1 answer
41 views

How to design a fridge / freezer / air conditioner / heat pump?

I have this question / problem in my mind for an estimated of ~20 years. Obviously, my life does not depend on the solution, but the quality of the life of my brain might get improved :) Shortly: How ...
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Nozzle inlet and outlet diameter for a shell and tube heat exchanger

Hi I have designed a shell and tube heat exchanger to cool octane and water. I have all the dimensions but I was unsure which equation to use to calculate the diameter for the inlet and outlet nozzles....
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2 answers
57 views

Maximum rate of heat transfer in a balanced counter flow heat exchanger in NTU method

In effectiveness NTU method for heat exchangers, we have effectiveness of the heat exchanger defined as $$\epsilon = \frac{Q_{actual}}{Q_{max}}$$ Where $$Q_{max} $$ is the maximum rate of heat ...
1 vote
1 answer
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In this scenario, if I continue to increase the length of heat exchanger how will the temperatures change?

Consider a counter flow double pipe heat exchanger inside which the cold fluid enters at 20 degrees Celsius and hot fluid enters at 100 degrees Celsius. Initially the length of the heat exchanger is ...
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1 answer
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Maximum rate of heat transfer in Effectiveness NTU method for a heat exchanger

The effectiveness NTU method is used for determining the heat transfer rate for a heat exchanger, with known inlet temperatures and surface area. It makes use of effectiveness which is defined as $$\...
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1 answer
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Arithmetic and Log mean temperatuer difference of a double pipe heat exchanger with parallel flow

Consider a double pipe parallel flow heat exchanger, the mean temperature difference in this case turns out to be logarithmic because the temperature profiles are exponential. If we would have made ...
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How to model a condenser (heat exchanger) where both streams are two fluid mixtures?

As mentioned I would like to model a heat exchanger (using Python). In this case, the condenser/hx streams are both a mixture of O2 and N2 These are known for both streams: Inlet temperature Inlet ...
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3 answers
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Why does thermal conductivity of a pipe matter in a double pipe heat exchanger?

My understanding is that thermal conductivity is responsible for the time until something will heat up. For example, if you hold a copper bar over a candle it will quickly become hot at the other end. ...
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3 answers
94 views

How are heat exchangers normally calculated?

Most of the calculations that I find in books are about calculating the heat transfer rate, which I'm not sure why I would care about. What I imagine is the case in a real world situation is that I ...
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1 answer
166 views

In a shell and tube heat exchanger, does reducing flowrate affect the outlet temperatures?

Let's say I have 2 exchangers that are completely the same, only difference being that one of them has half the number of tubes. Also let's assume the coolant is the same and has the same inlet ...
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1 answer
63 views

How to transfer air heat easily?

Assume two buildings, one which generates a lot of air heat inside due to electrical equipment running etc. The buildings are 20-25 meters apart. Some questions: How can one easily transfer heater ...
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1 answer
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What is the fouling effect (in rate, foulant thickness) of sand inside tube side of a shell and tube heat exchanger?

I am working with RO reject which has high turbidity (mainly insoluble salts and also sand now). This is also my process stream and needs to go through a heat exchanger at 50-60C and flowing at 0.25m/...
2 votes
1 answer
42 views

Does a photon impart energy on a surface (to raise its temp) if it goes THROUGH that surface?

Hi so I have this senior design project involving cooling human skin as it is irradiated by an infrared LED. Human skin not only is super absorbent to IR, but that IR goes THROUGH the thickness of it ...
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3 votes
2 answers
244 views

Furnace Combustion Air Properties

My house is heated by a condensing natural gas furnace that is rated as 92% efficient. It has the option to draw combustion air directly from outside. I know the main advantage of this is avoiding ...
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1 answer
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What temperature could be achieved when nitrogen is used as a refrigerant in the heatpump?

Well we all are familiar that nitrogen is used to achieve low temperature. I was just wondering how can one determine the temprature that could be achieved when phase change of nitrogen is done from ...
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2 votes
2 answers
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Heat transfer Calculation, for Cooling for an aluminium box

To go into more detail, I basically have a controller and its housing is basically an aluminium box that I need to add heat sinks to. But first I need to calculate how much heat is being dissipated by ...
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1 vote
2 answers
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Heat Exchanger Design (Log Mean Temp Difference or Epsilon NTU Method)

I am trying to design two heat exchanger interfaces (shell and tube) that transfers heat to and from an intermediate heat pipe. The picture below gives a general idea of the problem I am trying to ...
1 vote
2 answers
42 views

When is a heat exchanger worth it?

I am currently working on a huge industrial process for a student project and we need to transfer around 25MW of energy between dozens and dozens of streams, some larger and some smaller ones. Many ...
1 vote
0 answers
25 views

How does energy recovery recuperator work

In a recuperator http://en.wikipedia.org/wiki/Recuperator, sensible heat can be transfered by thermal conduction through the plates, and latent heat can also be transfered when the high temperature ...
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4 votes
2 answers
3k views

Why Nusselt number for laminar flow in a pipe is independent of reynolds number

I understand that for fully developed flow inside a tube (with constant properties), Nusselt number doesn’t change in axial direction but it is surprising that it is also independent of Reynolds ...
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1 answer
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In a diesel engine, does more heat leave the engine through the tailpipe or the radiator?

Diesel exhaust is hot, and there's a lot of it. Diesel radiators also get pretty hot. In a typical diesel engine, which one is dissipating more heat? EDIT: In response to a request for specificity ...
2 votes
1 answer
30 views

Why do plate exchangers typically serve lower pressure fluids than shell and tube heat exchanger?

According to Wikipedia http://en.wikipedia.org/wiki/Heat_exchanger, plate exchangers typically serves lower pressure fluids than shell and tube heat exchanger, why? Tubes in plate exchangers are ...
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3 votes
1 answer
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How to periodically shut down a recirculating hot water solar thermal system

I am posed with a scenario where a hot water solar thermal system has been setup. The system comprises of a cold water tank, heating arrays and then a hot water tank. The system is closed loop and ...
1 vote
2 answers
73 views

why not put the compressor right next to the evaporator?

the cold line from evaporator to compressor will gain tons of heat on a super hot day even with insulation. if they put the compressor right outside the evaporator, both of the long lines will be hot ...
1 vote
0 answers
43 views

How can we dissipate the heat from a block of 10*10*3 mm with 100 degree Celsius without losing the portability of the block?

I have a Peltier's device of 10*10*3mm and the material is Bismuth Telluride. The hot side is 100 $^oC$ and I want to dissipate the heat, and at the same time, the device should be portable i.e. it ...
1 vote
1 answer
91 views

Heat Exchangers

LMTD of a counter flow heat exchanger is 20°C and cold fluid enters at 20°c & hot fluid at 100°C, mass flow rate of cold fluid is twice that of mass flow rate of hot fluid. $C_p$ of hot fluid is ...
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1 answer
181 views

Average Nusselt number or heat transfer coefficient to compare better heat transfer?

I'm simulating different arrays for cylinders in a simple cross flow heat exchanger (cylindrical pipes) as shown below: Inlet temperate(300K) is constant and the cylinders are at constant temperature(...
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1 answer
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Heating hot air within a 2 inch tube

Background So I am working on a project to where I am trying to heat up air within a 2 inch tube, with high air flow. I am using 2 inch tri clamp stainless steel tubes where I basically have a fan ...
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Are there any books which show how to design electrical coil heat exchangers?

I need to design an electrically powered gas heater, but i need to do so in detail. I'm looking for a guide similar to the shell and tube heat exchanger design guide in coulson and richardson's ...
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Search for comprehensive term for plants with heat generation with heat storage and operating states

My master thesis deals with systems with several operating states that generate heat and store it in a heat storage. Thereby I analyze combined heat and power plants with combustion engines, but also ...
1 vote
1 answer
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How to control precisely the wall temperature of a tubular reactor?

I have modelled a multi-tubular reactor performing a Fischer-Tropsch synthesis of alkanes and I was wondering about the stability of such a reactor. Even a very tiny deviation of the wall temperature ...
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1 answer
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Modelling reactor jacket with or without insulation, how to proceed?

I am currently trying to derive a model to help estimate as precisely as possible how much time can be saved by insulating the jacket of a reactor used for eating and cooling. EDIT: I edited my post ...
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380 views

Calculating geothermal heat pump

So I need to calculate how big geothermal heat pumps I need for a building. Heat pump is used for heating and to heat used water. If I know how many kW's are needed for heating the building and the ...
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2 votes
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Does a closed loop biomass-fired cogeneration/CHP make sense?

I'm working on a project concerning electricity production using biomass, and we have seen that making use of cogeneration is very attractive in order to increase the efficiency of the installation. ...
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2 answers
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Thermal oil in Boiler not reaching desired temperature

The thermal oil Feroline U in Boiler is not gaining the desired temp of 240 Degrees. We have physically measured the temp using digital thermometer at a distance of 20 cm where the boiler temp sensor ...
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3 votes
1 answer
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estimating the surface area of a steam coil immersed in a tank

I've been tasked to design a steam coil that will be immersed into a tank in order to maintain the fluid temperature above 25C (but not to exceed 40C), and I need to calculate its surface area & ...
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2 votes
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267 views

Choosing sides of a shell and tube heat exchanger for oil cooling

I recently took a quiz from POWER magazine that asked the following question: In a typical cooling system for lubricant oil in a gas turbine, which configuration is preferred to prevent leaks and ...
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1 vote
1 answer
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Deciding on number of tubes to construct a heat exchanger

I’m a chemical engineering student and I’m learning about heat exchangers,I came across this question and had a doubt , Cold water is heated from 20 degree C to 85 degree C while hot process stream ...
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1 answer
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Process fluid flow in a fired heater

While I’m studying about a fired heater (furnace) in chemical engineering , I learnt that the process fluids enters from the convection section and leaves at the radiant section of the furnace. Why ...
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2 answers
433 views

Valve first,then heat exchanger OR heat exchanger first then valve

In my exam, I was given 2 options to design a process. Assuming a saturated liquid coming out from the separator, A) should the stream pass through a valve to reduce pressure, then to heat exchanger ...
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1 answer
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Heat Exchanger Design- Cooling a gas mixture

I am designing a process heat exchanger to cool a gas effluent stream consisting of 70% Nitrogen 23% Carbon Dioxide and 7% Water (all mole percent). The stream is going to enter at 250 degC and 1....
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1 answer
277 views

Most effective heat transfer in a vertical pipe with small top/bottom temperature difference?

What would be most effective way to transfer heat in the following situation? Specific conditions: A vertical cylinder or pipe, 30-100cm long, 5-10 cm in diameter, heavily thermally insulated except ...
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1 answer
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Maximizing radiator cooling while minimizing fan noise

I've got the following idea in mind. I have a water-cooled PC, I wish to minimize fan/pump noise by lowering their speeds, while maximizing the cooling that can be done. There is the simple solution ...
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3 votes
2 answers
108 views

Heat exchanger design guidance

I need to design a water to air heat exchanger with a blower for a small greenhouse as an engineering project. There aren't much design specifications - only that it must maintain a temperature of ...