What is NTU method for heat exchanger?
The Number of Transfer Units (NTU) Method is used to calculate the rate of heat transfer in heat exchangers (especially counter current exchangers) when there is insufficient information to calculate the Log-Mean Temperature Difference (LMTD).
How do you solve NTU?
NTU method formula:
- R (specific heat ratio) = CminCmax.
- And, NTU = UACmin.
- Where, R = CminCmax.
- and, NTU = CUACmin.
- ∴ R = CminCmax=Cmin∞ C min C max = C min ∞ =0.
- ∴R=CminCmax=1.
- ∴ɛ=QactualQmax.
- R = CminCmax C min C max =62500189000 = 0.3306.
What is LMTD and NTU method?
The LMTD method is convenient for determining the overall heat transfer coefficient based on the measured inlet and outlet fluid temperatures. The ε-NTU method is more convenient for prediction of the outlet fluid temperatures if the heat transfer coefficient and the inlet temperatures are known.
Where can I find NTU heat transfer?
By now our Q Max. Or. We can define it in terms of the cold fluid again divided by Q max for any heat exchanger the effectiveness is going to be a function of NTU and C sub R where NTU is known as the
What does NTU represent?
NTU stands for Nephelometric Turbidity unit, i.e. the unit used to measure the turbidity of a fluid or the presence of suspended particles in water. The higher the concentration of suspended solids in the water is, the dirtier it looks and the higher the turbidity is.
What does NTU indicated?
NTU indicates the overall size of the heat exchanger.
What is NTU and HTU?
N = number of transfer units (NTU) – dimensionless. H = height of transfer units (HTU) – dimension of length. The number of transfer units (NTU) required is a measure of the difficulty of the separation.
What is LMTD formula?
Formula for LMTD calculation –
For a Parallel Flow Heat Exchanger, Hot fluid entering at temperature 100 degree Celsius and exiting at 90 degree Celsius . Cold fluid Entering at 30 degree Celsius and exiting at 50 degree Celsius. Find the LMTD . LMTD = ((100 – 30)-(90-50)) / ln (100-30/90-50) = 53.6 degree Celsius .
What is the physical significance of NTU?
NTU is the number of transfer units. UOverall is the overall heat transfer coefficient between fluid 1 and fluid 2. ROverall is the overall thermal resistance between fluid 1 and fluid 2. AHeat is aggregate area of the primary and secondary, or finned, heat transfer surfaces.
What is NTU in distillation column?
The number of transfer units (NTU) required is a measure of the difficulty of the separation. A single transfer unit gives the change of composition of one of the phases equal to the average driving force producing the change. The NTU is similar to the number of theoretical trays required for trayed column.
What is the formula for heat transfer?
Q=m \times c \times \Delta T
Here, Q is the heat supplied to the system, m is the mass of the system, c is the specific heat capacity of the system and \Delta T is the change in temperature of the system. The transfer of heat occurs through three different processes which are, Conduction, Convection, and Radiation.
What should be the value of NTU?
NTU is defined as:[11.74]NTU=UACminwhere U is the overall heat transfer coefficient (kW/m2K), A is the heat transfer area of the heat exchanger (m2) and Cmin is the smallest thermal capacity of the two fluids (kW/K).
What is the physical significance of NTU in mass transfer?
What NTU stands for?
Why LMTD is used in heat exchanger?
The log mean temperature difference (LMTD) is used to determine the temperature driving force for heat transfer in flow systems, most notably in heat exchangers. The LMTD is a logarithmic average of the temperature difference between the hot and cold streams at each end of the exchanger.
What is fouling factor?
The fouling factor represents the theoretical resistance to heat flow due to a build-up of a layer of dirt or other fouling substance on the tube surfaces of the heat exchanger, but they are often overstated by the end user in an attempt to minimise the frequency of cleaning.
What is the efficiency of heat exchanger?
The heat exchanger efficiency is defined as the ratio of the actual rate of heat transfer in the heat exchanger, q, and the optimal rate of heat transfer, qopt,(1) η = q q opt = q U A ( T ‾ – t ¯ ) The optimum (maximum) rate of the heat transfer is the product of UA of the heat exchanger under consideration and the …
What are the 4 methods of heat transfer?
Various heat transfer mechanisms exist, including convection, conduction, thermal radiation, and evaporative cooling.
What are the 3 formulas of heat?
Different formulas for Heat
- H = (VI)t.
- H = (I 2 R)t.
- H = (V 2 /R)t.
What is effectiveness-NTU?
What is the effectiveness-NTU method? Similar to the LMTD (log mean temperature difference), the effectiveness-NTU method is a method used to analyze heat exchangers. This one is preferred when the outlet temperatures of the fluids are unknown, since, in these cases, the LMTD requires a cumbersome iterative solution.
How do you calculate turbidity?
The best way to measure turbidity in a wide variety of samples is with a nephelometer, also known as a turbidity meter. Turbidity meters utilize a light and photo detector to measure light scatter, and read out in units of turbidity, such as nephelometric turbidity units (NTU) or formazin turbidity units (FTU).
Why is turbidity measured?
Because turbidity is a measure of the clarity of water, it is a useful methodology to determine the ‘quality’ of water in the sample. Typical drinking water is clear and colourless with a very low – almost zero – turbidity value.
What happens when LMTD is zero?
Zero LMTD means no further heat transfer is possible and if heat transfer is to be done than infinite area is required, which is not possible.
What is F factor in heat exchanger?
here F (< 1) is interpreted as a geometric correction factor, that when applied to the LMTD (Log Mean Temperature Difference) of a counter flow heat exchanger, provides the effective temperature difference of the heat exchanger under consideration.
How do I reduce fouling?
The best way to avoid particulate fouling is to keep the cooling water clean and thereby prevent particles from entering the heat exchanger. However, in all cooling systems, and especially when using open cooling systems (with cooling towers), there will always be particles present in the cooling water.