Common conversion factors
 Details
 Category: Water Treatment
1 ft = 0.3048 m = 30.48 cm 
1 in = 2.54 cm = 0.0254 m 
1 m = 3.2808 ft = 39.37 in = 1.0936 yd 
1 km = 0.62137 mile 
1 mm = 1000 microns 
1 micron = 1/100000 m = 1/10000 cm 
1 kg = 2.205 lb 
1 lb = 453.592 gm = 0.45359 kg 
1 gm = 0.002205 lb = 15.432 grain 
1 slug = 32.1739 lb 
1 in sq.= 6.4516 cm sq. 
1 ft sq.= 929.03 cm sq. = 0.0929 m sq. 
1 cm sq. = 0.165 in sq. 
1 m sq. = 10.7693 ft sq. = 1.196 yd sq. 
1 in cube = 16.387 cc 
1 liter = 1000 cc = 61.024 ft cube 
1 gallon = 4.546 liters = 0.1605 ft cube 
1 m cube = 35.3148 ft cube 
1 ft cube = 0.028 m cube 
1 gm/cc = 62.33 lb/ft cube 
1 lb/ft cube = 0.016 gm/cc = 16 kg/m cube 
1 liter air = 1.2982 gm at NTP 
Deg F = (1.8 >< deg C) + 32 
Deg C = (Deg F – 32)/1.8 
Deg K = deg C + 273.15 
1 Bar = 750.06 mm Hg = 401.85 in water 
1 Bar = 0.98692 atm = 14.504 lb/in sq. 
1 Bar = 100000 kg/msec sq = 1000000 kg/cmsec sq. 
1 N/m^{2} = 1 pascal = 1/100000 bar 
1 N/m^{2} = 1 kg/msec^{2} = 10 g/cmsec^{2} 
1 N/m^{2} = 1.4504/10000 lb/in sq. 

Thermal conductivity 

1 watt/mK = 0.5778 btu/hrftdeg.F 
1 watt/mK = 0.8598 k cal/hrmdeg C 
1 watt/mK = 2.309 >< 10^{3} cal/seccm deg K 
1 K cal/hrdeg C = 1.1623 watt/m deg K 
1 K cal/hrdeg C = 0.6719 btu/hrftdeg F 

Heat transfer coefficient 

1 watt/m sq deg K = 10^{4} watt/cm sqdeg K 
1 watt/m deg K = 0.86 k cal/m sqhrdeg C 
1 cal/m sqhrdeg C = 4.184 >< 10^{4} watt/m sq. – deg K 
1 btu/ft sq.hrdeg F = 506782 watt/m sq. deg K 
1 btu/ft sq.hrdeg F = 4.883 kcal/m sqhrdegC 
1 kcal/m sqhrdeg C = 1.163 watt/m sqdegK 
Methods of checking steam condenser performance
 Details
 Category: Water Treatment
It is desirable to get a rated load or some agreedupon load on the turbine which will be the same for each successive check and read the load, air leakage, inlet water temperature, outlet water temperature and the absolute pressure in the condenser, and convert the absolute pressure into the corresponding saturated steam temperature; also, calculate the temperature rise, initial temperature difference and terminal difference.
The terminal difference is the difference between the steam temperature and the outlet water temperature; the temperature rise is the increase in the CW temperature. The initial temperature difference is the difference between the inlet water temperature and the steam temperature (or the saturation temperature corresponding to the absolute pressure).
If this data is recorded periodically and checked, any deviation will give the operator the best indication of what has been happening to his condenser.
During a period of high air leakage, when air blankets tube surfaces, the absolute pressure, air leakage, steam temperature and terminal difference will rise and again upon correcting the leakage, will return to normal. Also, during a period of dirty condenser tubes, the absolute pressure, steam temperature and terminal difference increases and after cleaning will return to normal. This holds true with noncondenser type heat exchanger.
Other factors:
Other factors, which would affect the condenser trend, are the change in water inlet temperatures and change in loads. These changes do not affect the condenser performance although they change most of the condenser temperature values and do change the condenser backpressure. As a guide to condenser performance the terminal difference gives the operator the alarm and should be watched carefully.
Data taken at a different lad may be compared to that at the desired load by the following device. Load to the condenser, either in terms of BTU per hour or kw load plotted against rise and initial temperature difference. “Rise” will be a straight line from zero at no load to maximum rise at full load. Disregarding the effects of air leakage and vacuum pump capacity and some of these matters in the very low load range, the initial temperature difference will also be a straight line.
Operators should watch pump discharge pressures and pump horsepower for clues as to tube sheets plugged by rubbish accumulation. These indications can also be obtained from delta P of CW across the condenser.
Poor heat transfer due to tube fouling will affect vacuum performance at all loads but will be most noticeable at high loads.
Circulating water pump data to approximate water flow, which with rise in circulating water temperature gives another approximation of heat load.
The condenser performance is evaluated, expressed as percentage:
% = U actual >< 100
U designed
U actual can be calculated as: U = Q/A∆Tlmtd
U actual = actual heat transfer rate, btu/hr/sq ft/deg F Lmtd
Q = duty, Btu/hr
Significance of pressure
 Details
 Category: Water Treatment
The cold and hot fluid inlet and outlet temperature and ΔP of the fluids across the heat exchangers are very significant in determination of the health of that heat exchanger. In condensers ΔP is shown as vacuum. Any increase in ΔP or decrease in vacuum is an indication of fouling or decrease in flow rate of the fluid.
Increase in ΔP for hot fluid when the inlet hot fluid P remains same, across a heat exchanger could be due to fouling on the heatexchanging surface exposed to the hot fluid. The same applies to CW side. An increase of ΔP with an increase in inlet P is very much possible.
In condensers the decrease in vacuum could be due to fouling on heatexchanging surface on both or either side. Most probably it will be due to fouling of heatexchanger surface on CW side. In condensers the decrease in vacuum could also be due to leakage from the heatexchanging surface or from the surface exposed to atmosphere.
It is important to know the design pressure on both sides (hot & cold). The highpressure fluid may ingress in lowpressure fluid. Normally the hot fluid pressure is higher than cold fluid pressure.
Change in ΔP 
Indication 
Increase, in hot fluid 
Increase in flowrate of hot fluid Fouling on HE surface on hotfluid side 
Decrease, in hot fluid 
Decrease in flowrate of hot fluid Leakage on hot fluid path. 
Increase, in cold fluid 
Increase in flowrate of cold fluid Fouling on HE surface on coldfluid side 
Decrease, in cold fluid 
Decrease in flowrate of cold fluid Leakage on cold fluid path. 
It is important to know the design pressure on both sides (hot & cold). The highpressure fluid may ingress in lowpressure fluid. Normally the hot fluid pressure is higher than cold fluid pressure.
Significance of flowrates
 Details
 Category: Water Treatment
Flowrates and any change in flowrates have different effects on Q and U values. Following are the effects:
Changes 
Effects 
If hot fluid flow rate is increased 
The ΔP of hot fluid across the heat exchanger will increase. The inlet P of hot fluid will increase The ΔT of hot fluid will decrease The ΔT of cold fluid will increase The Q value will increase 
If hot fluid flow rate is decreased 
Viceversa of the above effects 
If cold fluid flow rate is increased
If cold fluid flow rate is increased 
The ΔP of cold fluid across the heat exchanger will increase. The inlet P of cold fluid will increase The ΔT of cold fluid will decrease The ΔT of hot fluid will increase The Q value will increase The fouling/scaling propensity of Cold fluid will decrease The flow induced corrosion/erosion may increase 
If cold fluid flow rate is decreased 
The ΔP of cold fluid across the heat exchanger will decrease. The inlet P of cold fluid will decrease The ΔT of cold fluid will increase The Q value will decrease The fouling/scaling propensity of Cold fluid will increase Avoid such situations 
Condenser, where the hot fluid temperature varies
 Details
 Category: Water Treatment
In some type of heat exchanger, the temperature of both the fluids is varying and there fore logarithmic mean temperature will have to be calculated. The temperature changes of water and hot fluid may be represented graphically by the following figure. During the process the hot fluid will reject heat in the following manner:
(a) To cool down to saturation temperature, (process DC)
(b) To liquefy (process CB)
(c) To subcool the liquid (process BA)
At the same time the water will receive heat and will get heated from tc1 to tc2.
This type of condenser may be assumed to consist of three sections i.e. (i) desuperheater (ii) liquefier (iii) subcooler.
Here if th1, 2, 3 & 4 is known then LMTD of each section can be calculated and average mean temperature difference is approximately given by:
ΔT m = total heat rejection (HR) (kJ/min) (eq. 1.35)
(HRDC/ ΔT m (DC)) + (HRCB/ ΔT m (CB)) + (HRBA/ ΔT m (BA))
And then with this LMTD values for Q and/or U can be calculated.