How do you choose a shell and tube heat exchanger?

How do you choose a shell and tube heat exchanger?

Tips on Selection of Shell and Tube Heat Exchangers

1. Measurement of Heat Load.
2. Levelling-Off Temperature.
3. Natural Radiation Cooling.
4. Estimating Heat Load.
5. Maximum Heat Exchanger Capacity.
6. Heat Generation in the System.
7. HP = GPM × PSI ÷ 1,714.
8. Cooling Water.

How do you calculate the heat transfer area of a shell and tube heat exchanger?

The main basic Heat Exchanger equation is:

1. Q = U x A x ΔTm = The log mean temperature difference ΔTm is:
2. ΔTm = (T1 – t2) – (T2 – t1)
3. = °F. Where:
4. T1 = Inlet tube side fluid temperature; t2 = Outlet shell side fluid temperature;
5. ln (T1 – t2) (T2 – t1)

How does heat transfer work in a shell and tube heat exchanger?

Heat transfer mode in a shell-and-tube heat exchanger usually involves convection in each fluid and conduction through the wall separating the two fluids.

How many times do we calculate for pressure drop in a shell and tube heat exchanger Mcq?

4. How many times do we have to calculate for Pressure drop in a Shell and Tube Heat Exchanger? Explanation: For a Shell and Tube HE, we have to calculate pressure drop twice, once for the tube to check whether the equipment can handle that pressure. Similarly, the second time for the shell side.

How is shell side heat transfer coefficient calculated?

Shell Side Heat Transfer Coefficients

1. Ds, the shell inside diameter.
2. fB, the fraction of the shell cross-section that makes up the baffle window.
3. Nbt, the number of tubes in the baffle window (usually approximated by fb*Ntubes)
4. PB, the baffle pitch (spacing)
5. pt, the tube pitch.
6. do, the tube outside diameter.

Why is heat flux negative?

Both latent and sensible heat fluxes are negative because the ground is cooling and water vapor is condensing, leading to a positive gradient in temperature and specific humidity. The subsurface ground is warmer than the surface, so there is an upward energy flux from the subsurface to the surface.

Is heat a vector or scalar?

Heat is a scalar quantity because it is not obey vector addition laws.

Is heat flow out positive or negative?

Heat, presented by the symbol Q and unit Joule, is chosen to be positive when heat flows into the system, and negative if heat flows out of the system (see Figure 17.1). Heat flow is a results of a temperature difference between two bodies, and the flow of heat is zero if TS = TE.

Is heat transfer positive or negative?

According to the classical sign convention, heat transfer to a system and work done by a system are positive; heat transfer from a system and work done on a system are negative.

Is heat absorbed negative or positive?

When heat is absorbed by the solution, q for the solution has a positive value. This means that the reaction produces heat for the solution to absorb and q for the reaction is negative. When heat is absorbed from the solution q for the solution has a negative value.

What does it mean when Q is negative?

exothermic

What does it mean if entropy is negative?

A negative change in entropy indicates that the disorder of an isolated system has decreased. For example, the reaction by which liquid water freezes into ice represents an isolated decrease in entropy because liquid particles are more disordered than solid particles.

How do you know if a process is spontaneous?

When ΔS > 0 and ΔH < 0, the process is always spontaneous as written. When ΔS < 0 and ΔH > 0, the process is never spontaneous, but the reverse process is always spontaneous. When ΔS > 0 and ΔH > 0, the process will be spontaneous at high temperatures and non-spontaneous at low temperatures.

What is the difference between spontaneous and nonspontaneous processes?

The main difference between spontaneous and nonspontaneous reactions is that spontaneous reactions release free energy from the system, making it more stable whereas nonspontaneous reactions increase the total energy of the system.

Which is not a spontaneous process?

Therefore, flow of heat from a cold body to a hot body is a non-spontaneous process as it requires external work as per Clausius.

What is non spontaneous process give example?

Examples of non-spontaneous processes: 1) Flow of heat from inside of refrigerator to the room. Room is at higher temperature than refrigerator. 2) Boiling of water.

Is salt dissolving in water spontaneous?

When NaCl (table salt) dissolves in water, the reaction is endothermic. Yet, when added to water, it dissolves easily (spontaneously) without added energy.