August 23, 2009

Small Water Saving Initiative from my company

Dear All,
I just wanted to share a small initiative of my new company towards saving of water. This can be presented by you to your management for implementation which will help us to keep our globe safe and provide sufficient water savings for many families to upkeep their daily life.

The water is very important for all living things and currently it is of utmost importance for any coroporate house, individual, and governments to conserve water & promote conservation fo water.

In our present company the management has implemented waterless urinals in the corporate building. This is saving around 2 Litres of water / day / person. We have around 400 people working in this office which is therefore, saving around 2 x 400 x 300 = 240000 Litre / Year.

Now see the importance of this number. Each family (4 persons) need around 100 litre of water / day for hygeine & drinking. Therefore, it can serve for 2400 families for 1 year OR 40 families for 60 years of average life.



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August 15, 2009

Steam Properties - II

In the previous post I discussed about P & T correlation for saturated steam. I also mentioned that its better to use Excel add-in than using these formulae in Excel sheet. However, these are essentially required if you are using some non worksheet based computer program for the evaluation / simulation of your project.

So here I will cover the other major property that is enthalpy & latent heat for steam.

2. Enthalpy of Saturated Steam at Given Temperature

Enthalpy Hv = alphat + gamma

alphat = 0.99615 t + 1.8239 x 10^-6 * t^2 -0.13468 x 10^ (-0.036 t) + 0.13468

gamma = 597.34 - 0.555 t - 0.2389 x 10^alpha

alpha = 5.1463 - 1540 / T

Where t = temperature in °C
T = temperature in K

So if you need to find out the enthalpy at a given P, you first need to calculate saturation temperature based on methods given earlier.

3. Enthalpy of Saturated Water at Given Temperature

Hl = 0.001 t2 + 0.8663 x t

Where Hl = enthalpy of Saturated liquid at t temperature in Kcal/Kg
t = temperaure in °C

4. Latent heat of Vaporization at Given Temperature

Lambda = Hv - Hl

Hv & Hl are calculated above.


5. Saturation temperature from Pressure
This part is also required frequently, so I developed an equation based on data from steam tables.

t = A x y^5 + B x y^4 + C x y^3 + D x y^2 + E x y + F
Where
y = Log10 (Pv)

A = 0.03878244
B = 0.5246778
C = 2.7767678
D = 12.6450237
E = 63.9525883
F = 99.082168

Pv is in Kgf/cm2.

List of other property estimation methods on this Blog.

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August 07, 2009

Ammonia Vapor Pressure & Temperature Equations

In the series of physical properties calculation methods, I am now covering Ammonia P & T correlations which are frequently used in refrigeration system design calculations. Or they may be used for designing of heat pumps - yes may be I don't know at this stage if one can use ammonia for heat pump service or not.


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Saturation Pressure vs Temperature.

This equation is valid for t = -75 to 70°C. I have limited this equation to this range for better accuracy of calculated data vis a vis comparison with published data.

Pv = A x T^5 + B x T^4 + C x T^3 + D x T^2 + E x T + F

where Pv = vapor pressure in Kg/cm2
T is temperature in Kelvin.

A = -4.5864778 x 10^-11
B = 9.85099347 x 10^-8
C = - 5.7526544 x 10^-5
D = 1.4773233 x 10^-2
E = -1.7847943
F = 83.3895705

Saturation Pressure vs Temperature for t > 70°C.

Pv = 89875.92511 exp (-2706.64791 / T)

where units are same as above.

Saturation Temperature Vs Pressure for P = 0 to 34 Kg/cm2.


T = A x y^5 + B x y^4 + C x y^3 + D x y^2 + E x y + F

Where
A = 0.13493672
B = 0.380555
C = 2.13810444
D = 10.058439
E = 45.5972648
F = 239.1719874

T is in Kelvin

List of other property estimation methods on this Blog.


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