9

You just need to convert the volumetric flow rate to a mass flow rate by multiplying by its density. This is easy for water: $$10\ \mathrm{l/hr} \cdot 1\ \mathrm{kg/l} = 10\ \mathrm{kg/hr} = 10^4\ \mathrm{g/hr} = \frac{10^4}{3600}\ \mathrm{g/sec} = 2.78\ \mathrm{g/sec}$$ Now you can multiply by the specific heat and the temperature rise to get the power ...


8

What we usually care about when selecting a material for a heat exchanger is its thermal conductivity. The higher the thermal conductivity, the easier it'll be to transfer heat between the two fluids. This means that we'll either (a) be able to create a larger temperature difference using a material with a higher thermal conductivity in a heat exchanger of a ...


7

The efficiency of any radiator (heat exchanger) is a function of the temperature difference between the two fluids in question. All else being equal, a heat exchanger with a greater temperature differential will transfer more heat. Each radiator will have a temperature gradient across it. (Here I'm talking about how much the temperature of each fluid ...


7

If your question means, "for a given surface area and wall thickness, is there anything that performs better than Copper", then the answer is - "Unless you are prepared to make your heat exchanger from diamond or silver, then, no." However, if you change your question very slightly to "Is some other material than Copper sometimes ...


7

They are very nearly equal for typical four-stroke non-turbo diesels under load. A turbo diesel under load should have slightly more radiator loss than exhaust loss. At the bottom is a link to the technical spec sheet for a Cat 3412 powered genset. It's a probably a bit bigger than what you had in mind. It is a turbo with aftercooler (A/C in the doc below). ...


5

the outside air is colder, but the flame temperature is still much much hotter than that so the difference cold inlet air makes on the outlet temperature of the furnace will be small. The same commentary applies to the density argument: yes, but the effect is small. The fact that the outlet air is at 43 C represents the 8% efficiency loss of your furnace. ...


4

I found the average of the inlet and outlet pressure and temperature in the hydrocarbon stream and then used those values in the ideal gas equation to find the densities of each hydrocarbon Why would you find the density of each hydrocarbon? you now have a mixture flow and you need to find the thermal properties of this mixture for your heat transfer ...


4

$$P = \dot m \cdot C_p \cdot \Delta T $$ Where $P$ is the power required in Watts ($Joules/sec$) $\dot m$ is the mass flow rate ($kg/sec$) (you'll have to convert the volumetric flow given to a mass flow rate by using $\dot m = Flow_{Vol} \cdot \rho$ where $\rho$ is the density of the fluid) $C_p$ is the specific heat of the fluid ($ \frac{Joules}{...


4

One thing to consider is that pipes used for heating like this are normally « finned » to increase the surface area - fins can be small discs fitted to the pipe or even wire loops - both increase the surface area massively and reduce the length required. This article explains the finned pipe although they are collecting heat: The performance of a coiled ...


3

10 litres per hour 10 kg per hour 10,000 g per hour 166.66 g per minute 2.77 g per second Every second, you need to raise the temperature of 2.77 g of water by 30 °C. 2.77 g of water 4.18 J/g specific heat 11.6 J every second for 1 degree 348 J every second for 30 degrees Assuming 80% efficient. 348 J / 80% = 435 J You need 435 J/s. Joules per second ...


3

$\triangle max$ and $\triangle min$ are not defined as maximum and minimum temperature differences in a heat exchanger. Quoting from Wikipedia: The LMTD is a logarithmic average of the temperature difference between the hot and cold feeds at each end of the double pipe exchanger. $${ \triangle T_{max} = 400-120 = 280 \text{ F}}$$ $${ \triangle T_{min} = ...


3

I'm going to have to make this an answer. If someone feels it's inappropriate I can delete it, what follows is the start of my comment. Grin, I bought my house with an outdoor wood stove, we have a love/ hate relationship. I love: It burns all my waste paper and meat products, (Including the treats our cats bring us, and the scraps the dogs drag home ...


3

I think the key information is that the liquid is saturated. This means any reduction in pressure will lead to partial vaporization and two phase flow. For heat tranfer best overall heat transfer coefficient is always direct to liquid rather than vapor. You still will have vaporization once the saturated liquid once it enters the heater, but the effect ...


3

The evaporator is usually in the area to be cooled ie where the people work, read etc As the compressor takes space and tends to be noisy it is located away from that area. That makes the system in the « active » area smaller and quieter.


3

There is quite a bit to unpack here, so I may need to deconstruct your question a bit. Your question is surrounding the fouling rate of a Shell & Tube (S&T) heat exchanger which I will get to, but there are a few things with respect to the RO that must be addressed. If you have sand in the feedwater to your RO, you have much bigger issues than heat ...


2

I can't speak from real (=hands on with my own hands) experience, but in industrial applications I see mostly shell and tube type HX. Exhaust is in the tubes, the shell has the water. Pros: lots of surface when you add flanges opposite the tube openings, cleaning is doable Cons: Pressure loss in the small tubes An alternative would be to jacket the (...


2

As stated the problem is probably not well enough constrained. Given the specification, the way you get minimum temperature out is to pump as much volume as you can through the primary and then regulate the input temperature to achieve desired output. I.e. the more primary flow there is the lower delta temperature drop you need in the primary side. Pumping ...


2

First, as Arthur notes, even the best Nusselt number correlations are often as much as 20% off, so don't expect any analytical method to give results that are much better than approximate. With that said, there are ways to compute the Reynolds number for shear thinning fluids. Rudman, Blackburn, et al suggest using the effective viscosity for the mean wall ...


2

No, not any material. Only materials with a higher thermal conductivity than copper will increase the rate of heat transfer. In some cases, you may get better heat transfer by using a stronger material that could be formed into a thinner pipe, but you're generally better off going for thermal conductivity.


2

Either your definition of "completely" is a bit unusual, or there's something wrong with those charts, because in those charts, 1.6 x the model does not completely match any of the six observations you have (assuming the point values are at the centre of each shape). Either way: your model outputs don't match your observations, with or without a 1.6 fudge ...


2

Between 135 F and 100 F I don't think the heat capacity or density would vary much so using average properties should be fine. If you want to be more conservative you can use the higher Cp between inlet and outlet as this would yield the highest cooling water flow requirement. If you want to be more accurate for whatever reason then you could integrate the ...


2

This is a good start for your decision and you can probably get away with it however you should factor in everything that influences that decision. Cleaning Corrosion Fouling Temperature Viscosity Pressure Pressure Drop Higher Temperatures and a higher pressure favor allocating the fluid to the tube site. Put a high-pressure fluid on the tube side. This ...


2

Assumptions: "Radiator" means a forced-air air-to-fluid heat exchanger. Radiators in either setup will pull from their own fresh air source (not from the exhaust of another radiator). Ignoring radiator design, natural convection, and internal fluid turbulence effects. Flow through parallel radiators is perfectly equal. The efficiency would be the same ...


2

It is just getting as much heat as possible. Heat flows from hot to cold. The convection section is a much lower temperature. The convection section is basically waste heat in flue gas. The cold process fluid is (pre) heated to recover some of the waste heat. The exit process fluid may be hotter than the flue gas. In any heat exchanger you should ...


2

Full Analysis Perfectly Insulated System The best case is to analyze this system in both the time and position domains. The time domain considers the variation of the reactor temperature $T_r(t)$ and the outlet temperature of the jacket system $T_{jL}(t)$. The position domain considers the variation of the temperature profile through the jacket $T_{j}(z)$. ...


2

I've had this problem before, albeit not with such a tight temperature range. I would recommend immersing the reactor in a fluid with high thermal mass, then I would circulate and temperature control the fluid. The circulation will minimize the effects of temperature differences. Water is ideal, but dangerous since it would have to be under pressure, and ...


2

What you describe is quite common where there isn't any problem with power and noise. It requires a bit more sophistication to manage the superheat. And yes, you need to quiet the thing some. I replaced a '60s era 20 ton compressor in a restaurant's dining room AC closet while they were serving dinner. This is also a good idea near the coast to keep the salt ...


2

I would not mess around like this at all. I would make a secondary heat dump (old radiator in the garden, swimming pool...) and divert excess heat there.


2

Because the plates are usually very thin for their dimensions and tubes tend to have more strength for the pressure loading. I would check better references such as Simonson: Heat transfer for more thorough detail instead of wiki...


2

The Nusselt number is about the ratio of conductive and convective heat transfer across a boundary. The Reynolds number is about how a fluid is moving - usually laminar (below 1700), turbulent (above 2000) or in-between aka critical. However these numbers are not absolute as laminar has been seen above 2000 in very carefully controlled conditions i.e. it is ...


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