# What is Heat exchanger: Definition and 166 Discussions

A heat exchanger is a system used to transfer heat between two or more fluids. Heat exchangers are used in both cooling and heating processes. The fluids may be separated by a solid wall to prevent mixing or they may be in direct contact. They are widely used in space heating, refrigeration, air conditioning, power stations, chemical plants, petrochemical plants, petroleum refineries, natural-gas processing, and sewage treatment. The classic example of a heat exchanger is found in an internal combustion engine in which a circulating fluid known as engine coolant flows through radiator coils and air flows past the coils, which cools the coolant and heats the incoming air. Another example is the heat sink, which is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant.

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1. ### Spec'ing the power of heater for an atypical heat exchanger problem

Homework Statement: Calculate the power of heating source required in a heat exchanger Relevant Equations: Heat transfer for LMTD heat exchanger. I have a real-world problem whereby: Water is flowing at a constant flow rate of 10 mL/min through a PVC tube, inner radius of 1.25mm and outer...
2. ### Engineering Water Flow from Pressurized Tank through Heat Exchanger

Hi All- New member here. As the title states I am trying to solve the flow volume of water from a pressurized storage tank through a heat exchanger and then discharging out the end of a pipe. I have been working on this for several days now without any luck, seems like now I am just throwing...
3. ### Cleaning of the finned tubes on gas cooler without disassembling

Hi, I've been thinking about the solution for cleaning a water-cooled gas cooler and would love to hear some advice from the smarter people with more experience. Description - I will try to roughly explain the concept. Gas Cooler is used to decrease exhaust gas temperature. The exhaust gas...
4. ### Heat sink - calculating temperature at the base

Hi, I've checked the literature but couldn't find any formulas or examples for this particular problem involving heat sink with straight fins: As you can see, I want to assume: - power at the bottom surface - convection (known ambient temperature and heat transfer coefficient) at the...
5. ### Writing: Input Wanted Best material for heat exchanger on a space ship

Looking for the best material for a heat exchanger exposed to vacuum in a space ship. I've initially gone with radiator vanes that are a ceramic blend and typically operate at twenty-five hundred degrees, but then I started wondering if there is a better material...and now I'm here, hoping for...
6. ### I Newbie learning Heat Exchanger

ΔTLMTDcf = 20 - 30 ln20/30 ←(What is "In"?) = 24.7°C ←(Why the answer is 24.7? How?)
7. ### Air-to-Water Heat Exchanger - Car radiator

I'm looking for a way to keep a liquid under 50°C. This liquid has a thermal conductivity of .1396 and a specific heat of 2.054 both at 40°C. and a constant energy source submerged in it ranging from 16KW to 17.5KW. I'm barely starting to read about this topic, according some forums, a car...
8. ### Heat Exchanger: +40C rise at 16 liters/minute flow rate

Summary:: How to calculate the rate of heat transfer between hot external water and cold internal water in a pipe. The image attached is my attempt at the question however, I find myself stuck trying to work out internal and external heat transfer coefficient.
9. ### HVAC Attic to Pool Heat Exchange, will car radiator collect heat?

My attic gets very hot even with the exhaust fan I installed. I would like to move than heat to my swimming pool. I currently have a FAFCO solar pool heater where the pool pump pumps water up onto my roof and thru the 12' long solar panel and down back into the pool. I would like to free up roof...
10. ### Condenser calculations - uncertainty

A water cooled plate condenser, condensing refrigerant. Heat exchanger (condenser with plates) characteristics: Description symbol value value (converted) number of plates np 28 number of channels nc 27 number of water channels nwc 14 number of flowing channels for refrigerant...
11. ### Hairpin heat exchanger design

Summary:: I need to know the preheat temperature of the water entering the gas boiler (which i think is the outlet temperature of the cold water Tc,o leaving the heat exchanger) Hi, I'm doing a design project of a hairpin heat exchanger. The problem is: In a public shower, the city water is...
12. ### Air to Air heat exchanger

I am considering building this type of heat exchanger, as I have seen several youtube videos on the build. The inside tube is aluminum, I am planning on building one from the top of my roof to nearly the floor, so ill say 5 feet. I am thinking of using a 1.5" inch aluminum tube, and bringing in...
13. ### Car Radiator as Air-to-Water Heat Exchanger

I am looking for a passive way to convert a supply of hot air into warm pool water. My pool can be in the low 70s without heat. Looking to get a 10 degree lift in pool temp. Pool is in-ground and relatively small at 8,500 gal. Water flow rate through the radiators can be regulated by valves...
14. ### Undefined log-mean temperature in heat exchanger design

For a course project, I need to design a heat exchanger to cool electronic components in an UAV. The heat exchanger will be cross-flow air to liquid. The cold side (air side) properties are evaluated at an altitude of 7620 m and -34.5 °C. For the hot side ethylene glycol - water solution with a...
15. ### A/C style heat exchanger instead of intercooler

I have supercharged my Toyota 4runner. The downside is the type of supercharger that I have bolted on (almost the only you can bolt on) replaces the intake plenum and has no way of cooling the air prior entering the combustion chamber. I read a little bit about how much heat is produced in the...
16. ### Calculate the number of plates required for a heat exchanger

Cooling water inlet temp is 4 degrees C Cooling water outlet temp is 80 degrees C Density of water is 1000 kgm-3 Specific heat water is 4.2kJkg-1K-1 Density wort is 1060 kgm-3 Specific heat wort is 4.0Kjkg-1K-1 Overall heat transfer coeff is 3000Wm-2k-1 Area of each plate is 0.75m2 For water...
17. ### Exit flow rate in a Plate Heat Exchanger

Hello All, I am working on a project with plate heat exchangers connected in a cascade system to heat up water connections in a huge system The Problem Statement : A boiler produces and circulates hot water at 65 degC to a Heat Exchanger and come out at 50 degC, where as the other fluid is...
18. ### Engineering Troubleshooting Heat Exchanger Error Msg

How should I do to eliminate the error message? In what direction should I approach the question? (I have tried difference combination and sequences of the heat exchanger below pinch, all seems not working) Thanks
19. ### Thermodynamic possiblity for outlet temperatures of heat exchanger

I have a heat & mass balance diagram wherein there is a shell and tube heat exchanger to recover heat from hot exhaust gas using cold water. The exhaust gas inlet temperature is 120°C and the outlet is at 40°C. The inlet water temperature is 35°C while the outlet water temperature is at 50°C...
20. ### Effectiveness to calculate the outlet temperatures of a heat exchanger

Because the specific heat capacity is lower for the hot fluid: ε=(T_hi-T_h2)/(T_hi-T_C1 ) 0.82=(140-T_h2)/(140-15) 140-T_h2= 102.5 T_h2= 140-102.5=37.5° I'm not sure if I'm actually on the right track here, if I am this is as far as I've gotten. I can't seem to then find an equation to...
21. ### Heat exchanger - efficiency of the cycle

Homework Statement Homework EquationsThe Attempt at a Solution Since we want the fluid to be in liquid state before entering a boiler, and super-heated water can only reach 374°C before entering super-critical state, suppose after the expansion, the temperature at point 3 is still higher than...
22. ### Design of a Double Pipe Heat Exchanger

Homework Statement It is desired to heat 5130 kg/hr of cold benzene from 80 to 120℉ using hot toluene using double pipe heat exchanger. Toluene will be cooled from 160 to 100℉. The specific gravities at 68℉ are 0.88 and 0.87 respectively. A fouling factor of 0.001 should be provided for each...
23. ### A heat exchanger is to be used to heat a process liquid with....

Homework Statement (c) A heat exchanger is to be used to heat a process liquid within the tubes using saturated steam at 100oC. The tubes have an inside diameter of 20 mm and outside diameter of 22 mm. It is estimated that the inner surface heat transfer coefficient will be 4.2 kW m-2 K-1 and...
24. ### Seawater sample temperature control – heat exchanger design

I’m designing a system where a sea water sample must have its temperature controlled between near its freezing point (-2°C) and +30°C to simulate sea temperatures. To control it, the sample will be in contact with a block, which will be controlled by an external circulating water bath. The image...
25. ### Heat exchanger, condensation

Homework Statement If you have a heat exchanger with a cooling fluid and a fluid that condenses, and the fluid condenses over the entire heat exchanger i.e. its temperature is constant. How can one make a heat balance in such a case, when dT is 0 for the condensing fluid but not the other? i.e...
26. ### Model developed from performance curves are dynamic models?

I am trying to model a real heat exchanger in simulink. I don't have the geometry data. But I have UA curve with me. If I have developed the model with UA curve, will it be dynamic in nature?
27. ### Heat exchanger and the second principle

Hello, I am developping a Python (/Pyomo) package for simulation and optimization of some industrial processes. I want to create global (simplified) models for heat exhangers (and more) and avoid differential equations. (to decrease the number of variables of the problem) Most often the...
28. ### Fin/Fan heat exchanger mass and energy balance

I am currently working on a project which requires a mass and energy balance on a fin/ fan heat exchanger. The problem I am running into is finding how to apply the fin efficiency to find out the amount of hea tbeing dissipated through the fins. The hot fluid is water and the cooling fluid is...
29. ### Maximizing Furnace Efficiency with Heat Exchanger Design: A Comprehensive Guide

Hello guys, I have a problem with my work! I have a furnance that have a "heat exchanger" to heat the air that will be used on the burners! (You can work every value close to 1 atm pressure on the entire exercice) The furnance is 1100~900 ºC The fan sends in a tube 7500m^3 air per hour...
30. ### Exam help regarding heat exchanger, forced convection questions

hello, im in bachelors mechanical engineering programme and my thermodynamics papers are in few days one question is related to heat exchangers or forced convection, but our professor has hinted that in the exam the question regarding heat exchanger, forced convection will be a case study of a...
31. ### DIY Heat Exchanger: Efficiently Heat Your Garage with Homemade Solution

Looking to make a heat exchanger so that I can have a less than adequately antifreeze treated water (easily over 750 gallons, so very expensive) from the outdoor wood boiler constantly circulating through a water jacket, and heat an adequately treated fluid (glycol treated water) and can turn...
32. ### Statements Based on a Heat Exchanger

Homework Statement Hello Everyone, We did an experiment using 3 types of heat exchangers this week, double-pipe, shell in tube and plate type. Water was flowing in the HEs, the temperature was set. We had to change the flow-rate only. After the experiment, we were given lots of online...
33. ### Calculating Temperature Change for Heat Exchanger

Hello, After the last post I completely changed the system. I now have a new system. Based on the feedback from last time I increased the time in contact with the block significantly. And I have made it a two stage unit. Here are the parameters for the first stage. An Aluminum block. (assume...
34. R

### Plate heat exchanger NTU method effectiveness

Hi All I need to do an evaluation of a pilot plant heat exchanger that we have installed and see if it would be better suited than our current bigger installations. I was trying to calculate the effectiveness of the heat exchanger but I keep on getting 1 with the NTU method. Below is the...
35. ### Shell and Tube Heat exchanger

Homework Statement 'A shell and tube exchanger is used to do heating, with single shell and 2 tube passes. There are 70 tubes each with an outside diameter of 25mm and length of each tube pass is 6m. ' I am wondering whether the 70 tubes are in between the 2 tube passes, or is it 1 tube pass...
36. ### Phase of refrigerant crossing heat exchanger devices

When a refrigerant crosses a heat exchanger device or has some heat added into it, like condenser/evaporator or boiler/cooling tower, does the phase always change? If that's so, why? Or do we need to check if the temperature is above or under the boiling point?
37. ### A Advanced Data Fitting - More than Simple Regressions

Hello All, I want to improve myself in data fitting in order to derive new equations for the data from experimental results and/or performance analysis. I am an engineering researcher and since I found some out-of-world formulations derived from performance data, I need to learn this advanced...
38. ### Double pipe heat exchanger

I'm trying to design a double pipe heat exchanger for two different water lines. One line is chilled water of approximately 7degC and the other is chilled water return from an air handling unit, of around 12degC. I want to design this heat exchange for a capacity of approximately 22kW. The part...
39. ### Convection heat exchanger

Hello guys, in the question attached, my understanding is that there is a heat transfer that heats the fluid from an initial at the input, to at the output. This heat transfer is via convection from walls of temperature . Firstly, . Because the walls are and the fluid is of a lower...
40. ### Maximum vapor velocity from a heat exchanger into a turbine

Hi Everyone, I am looking at designing a small impulse steam turbine that runs off of saturated refrigerant vapor delivered from a shell and tube heat exchanger. With the design of the turbine, I am looking to maximize the velocity that the steam can exit from a diverging nozzle in order to be...
41. ### Which Pressure Gauge Determines Saturation Temperature in a Closed Loop Pipe?

water is flowing in the closed looped pipe equipped with preheater. there are pressure and temperature gauges before the preheater and after the preheater. which pressure gauge should i use to know whether the outlet preheater temperature has reached the saturation temperature?
42. ### Optimizing Heat Transfer in Boiler Tubes: Tube Number & Length Calculations

Homework Statement flue gases = 50,000kg h^-1 surface area = 113.57m^2 Do = 25 + (3*2) = 31mm The tubes within a boiler are 25mm inside diameter with a wall thickness of 3mm. The flue gas velocity through the tubes is to maintain the overall heat transfer coefficient value and minimise...
43. ### Heat Exchanger Vs Cooling Tower?

Hey Guys ! what is the main difference between Heat Exchanger and Cooling Towers?
44. ### Heat exchanger and cooling towers design

I was wondering all the assumptions I need to make regarding a design for a heat exchanger and cooling tower design from a IC engine testbed. Each engines average output is 55kW and the water jacket temperature is 80 degrees (C) and has to be cooled to 65 degrees (C). The ambient atmospheric...
45. ### Calculation of water flow rate in heat exchanger

I am not a mechanical engineer; but I have physics background. I want to lift about 250 watts of heat from a metal block. At the same time I have to maintain its temperature at 30 deg Cel. For this I want to use water-air heat exchanger (HE). Heat exchanger will have inlet & outlet pipes. Hot...
46. ### Fluid Flow/Heat Transfer question struggle

Homework Statement I would really appreciate if someone could help me out with this exercise in fluid flow/heat transfer ,because I really struggling with it.Below I am attaching photo of problem+table with values. Thank you in advance !Homework Equations Question link:[/B]...
47. ### Sizing Heat Exchanger Flow

I'm trying to figure a range of flows of coolant that will pull 200,000 Joules per minute from a heat exchanger cooling oil. The oil is passing through a head that adds 200,000 Joules per minute to 0.5 L / min. The 0.5 L is dumped into a sump with ~7 gallons of oil. The oil then passes...
48. ### Cryogenic heat exchanger cooling power

Hi everyone! I have a silver plated copper heat exchanger (with an internal embedded circuit where liquid nitrogen flows) attached to a bigger aluminium block in order to cool it down. First, I want to estimate it's instantaneous cooling power during cool-down to a stable temperature. I have...
49. ### Design of plate heat exchanger

I am currently working on my college project about the design and optimization of plate heat exchanger. However, i have no idea where to start the project. Here is my first thought: - I set the hot and cold fluid to be water, 90 degC for the hot inlet and 30 degC for the cold inlet. - 50mm inlet...
50. ### Wall temperature in heat exchanger

My notes, using an example of a cold tube-side liquid cooling down a hot shell-side liquid stated that: ΔTb = TbS-TbT Mean tube-side wall temperature: TwT=TbT+(tube-side film resistance)/(total resistance) * ΔTb Mean shell-side wall temperature: TwS=TbS-(shell-side film resistance)/(total...