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a PocketPool : a design tool for swimming pool system designer |
Engineered design tools for swimming pool system designers, you can complete design in just a few clicks... find filtration pump flow rate, number of filter, balance tank volume, backwash tank volume, number of skimmer, amount of chemical required, chlorine solution dilution, heat-up heat, heat losses, etc.
Aim: creating a mobile design environment for the practising engineers & designers in today's mobile world.
Results: Instant solutions at your fingertips.
Highlights:
- calculates filtration pump flow rate, filter sizing, balance tank, backwash tank, skimmer, etc.
- built-in selections like turnover rate, filter type, filter area, filter loading rate, pool shape, pool area and volume calculation.
- design tool modules include:
a) Hypochlorite chlorination calculation.
b) Pool heat-up heat calculation.
c) Pool heat losses calculation.
- "save-to-file" function with built-in result file viewer.
- in SI-IP Units.
Calculation Example 1: Pool filtration sizing . . . |
Size the pool filtration system for the following pool.
W=33', D1=4', D2=6', L1=16', L2=16', L3=50' |
The following design calculations are done with aPocketPool program:
Worked Example (in IP units) Pool Filtration Calculations ======================= *** inputs *** Pool area = 2706 ft2 (using built-in area & vol. calculator) Pool volume = 109605 USgal Bathing load = 25 ft2/p Bather weight = 140 lb Wave action/displacement = 0.065 ft Turnover rate = 6 hr. Filter type = D.E. filter Filter loading rate = 2.5 gpm/ft2 Filter area (each) = 72 ft2 Backwash rate = 2.5 gpm/ft2 Backwash duration = 3 min. *** results *** Pump flowrate (USgpm) = 304.5 Filter area required (ft2) = 121.8 Nos. of Filter = 2 Wave displacement vol. (USgal) = 1316 Bather displacement vol. (USgal) = 1816 Backwash tank vol. (USgal) = 913 Balancing tank vol. (USgal) = 4045 |
Calculation Example 2: Chemical chlorination dosing. . . |
A pool water test has determined that a total chlorine dosage of 2 ppm (mg/L) is required to treat the pool water. The calcium hypochlorite has 65% available chlorine. Determine the weight of chemical (solid form) needed.
Also a 5% concentration solution needs to be prepared. Find the volume of the diluted chlorine solution.
The hypochlorite chlorination calculations presented below are based on the pool volume of 260 m^{3}.
*** Chlorine (Cl2) dose requirement *** Cl2 dose = 2 ppm *** Chlorine (100% strength) needed *** Pool volume = 260 m3 Cl2 dosage = 519.66 g *** Hypochlorite (chemical) required *** % available Cl2 in chemical used = 65 % Hypochlorite required: - solid form = 799.48 g - liquid form = 0.8000 litre *** Dilution of chemical concentration *** Final diluted solution concentration = 5 % Volume of diluted solution = 10.4000 litre Water added = 9.6000 litre |
how to size swimming pool heater ? how to calculate evaporation loss... |
Swimming pool water requires heating in two circumstances:
(1) during the operation, the pool is losing heat as a result of evaporation, convection, radiation and conduction (See Example 3). The magnitude of the evaporation + convection losses usually exceeds 80% of the total heat losses.
(2) during the initial heat-up (See Example 4).
In designing a pool heater, the designers usually have to evaluate the heating requirements for these 2 circumstances to make a fairly accurate estimate of the heater capacity. An understanding of the various losses is important.
Calculation Example 3: Pool heat losses . . . |
You are tasked to estimate the pool heat losses for a condominium lap pool (82 ft length x 33 ft width x 4 ft deep).
Given design conditions:
- Outdoor air conditions: 75 oF / 50% RH.
- Pool initial water temperature: 65 oF.
- Pool heated water temperature = 80 oF.
In doing the calculations, you have made the following assumptions:
a) wind speed = 7 mph.
b) conduction heat loss = 3% of total losses
c) ignore fresh water make-up heat loss.
Heat losses from a swimming pool are mainly attributed to the following four mechanisms:
- Evaporation from the pool surface.
- Convection from the pool surface.
- Radiation from the pool surface.
- Conduction through the pool walls.
Evaporation Loss:
The rate of evaporation is estimated from the following equation [ASHRAE 2011]:
Wp = [A(Pw-Pa)(0.089+0.0782V)]/Y
where
Wp = evaporation of water, kg/s
A = area of pool surface, m2
Pw = saturation vapour pressure at pool water temperature, kPa
Pa = saturation vapour pressure at ambient air dew point temperature, kPa
V = air velocity over water surface, m/s
Y = latent heat required to change water to vapour at surface water temperature, kJ/kg
The evaporation heat loss is then calculated as follows:
Qev = (Wp x Y) x F
where
Qev = evaporation heat loss, kW
F = activity factor
Convection Loss
The convection loss is calculated using the following equation [ASHRAE 2011]:
Qcv = A x hcv x (Tp - Ta)
where
Qcv = convection heat loss, W
A = area of pool surface, m2
hcv = convective heat transfer coefficient, W/(m2.K).
[If option for Fixed convective transfer coeff. is unchecked, hcv is computed as 1 + 0.3V btu/(h.ft2.oF) in the aPocketPool program; V in mph.]
Tp = pool temperature, oC
Ta = ambient temperature, oC
Radiation Loss
The radiation loss is calculated using the following equation [ASHRAE 2011]:
where
Qrd = radiation heat loss, W
A = area of pool surface, m2
Es = surface emittance.
[Es = 0.96 for water is used in the aPocketPool program.]
Tp = pool temperature, K
Tsky = apparent sky temperature, K
Tsky is estimated using the following equation [ASHRAE 2011]:
where
Esky = Sky emittance
Tdp = Ambient air dew point temperature, K
Note: For indoor pool, radiation heat loss is ignored in the aPocketPool program.
Conduction Loss
The conduction loss is small and can be ignored in general.
Note: allowance as percentage of total heat losses can be allowed for in the aPocketPool program.
Using the aPocketPool program, the heat losses calculated are presented below:
Mechanism | Heat Loss (BTU/hr) | % |
Evaporation | 374454.7 | 75.0 |
Convection | 41943.0 | 8.4 |
Radiation | 67637.4 | 13.6 |
Conduction | 14970.2 | 3.0 |
Total | 499005.3 | 100 |
Saturation vapour pressure at pool water temp. (in.Hg) = 1.033 |
Saturation vapour pressure at air dew point temp. (in.Hg) = 0.439 |
Ambient air dew point (oF) = 55.2 Apparent sky temp. (oF) = 53.9 |
Convective heat transfer coeff. (btu/h.ft2.oF) = 3.1 |
Note that the above calculated results are the peak or design heat losses based on the design conditions.
Calculation Example 4: Pool heat-up heating . . . |
If the owner wants to heat-up the pool in Example 3 in 24 hr, what is the pool heat-up heat required?
Before you determine the heat-up heat for the specific pool, the following operating conditions are noted:
a) Pool cover will be used during the initial heat-up period.
b) It is determined in Example 3 that evaporation, convection and radiation losses contribute 97% of the total losses. With pool cover, these losses and other minor losses such as conduction, etc. will be ignored.
The calculated heat-up heat required are presented below:
Pool volume = 80969 USgal Initial pool water temp. = 65 oF Desired pool water temp. = 80 oF Temperature difference = 15.00 oF Heat-up time = 24 hr Heat-up rate = 0.62 oF/hr Heat-up heat (output) = 423657 BTU/h |
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Need to calculate pipe pressure drop (head loss)?, see
Android's multiple Pipes Pressure Drop
or Windows' easy Pipe Friction Loop
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