mirror of
https://github.com/ssb22/bits-and-bobs.git
synced 2023-06-08 10:22:44 +00:00
118 lines
9.2 KiB
Python
Executable File
118 lines
9.2 KiB
Python
Executable File
#!/usr/bin/env python2
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# Python script to run the simulations for
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# http://ssb22.user.srcf.net/elec/oil.html
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# radiant heat due to lack of loft insulation ?
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# (+ not rm'ing so much moisture & therefore bettr ??)
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# http://web.archive.org/web/20140702232424/http://www.paulanthonywilson.com/blog/dyson-hot-review-a-scientific-approach/
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# didn't wait long enough for cool-down ? (only 1 reading)
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# NB it's "race to 22deg in 20mins then off", not continuous?
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# (AM09 review, most expensive whole-room one)
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# h = q / deltaT, h: heat transfer coefficient, W/(m2 K)
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# q = W/m2
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# Air: h = 10 to 100 W/(m2K)
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# If want to heat whole room (not just a spot) :
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# total thermal conductance (watts per kelvin)
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# try 15 for the oil rad (as heats up quite a lot while delivering 400W), 200 for the room
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# Where to find history:
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# on GitHub at https://github.com/ssb22/bits-and-bobs
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# and on GitLab at https://gitlab.com/ssb22/bits-and-bobs
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# and on BitBucket https://bitbucket.org/ssb22/bits-and-bobs
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# and at https://gitlab.developers.cam.ac.uk/ssb22/bits-and-bobs
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# and in China: https://gitee.com/ssb22/bits-and-bobs
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def simulate_heating_element(watts,onTemp,offTemp,medium,seconds=3600):
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# (NB onTemp,offTemp specified as deltas above 0=start)
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on = False ; totalOut = 0
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for second in xrange(seconds):
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if not on and medium.temp() <= onTemp: on = True
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elif on and medium.temp() >= offTemp: on = False
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if on:
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joules = watts # * 1 second
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medium.add(joules)
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totalOut += joules
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print second,
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medium.simulate_losses()
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for second in xrange(seconds,5400): # extra 30min cooldown
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print second, ; medium.simulate_losses()
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print "#",totalOut/3600000.0,"kWh consumed"
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class Medium:
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def __init__(self, J_per_K, W_per_K, nextMedium):
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self.heatCap = J_per_K # likely to change with temperature but this should do for now
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self.conductance = W_per_K # of wall to next medium
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self.nextMedium = nextMedium
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self.joulesAdded = 0
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def add(self,J): self.joulesAdded += J
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def temp(self): return self.joulesAdded * 1.0 / self.heatCap
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def simulate_losses(self):
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deltaT = self.temp() - self.nextMedium.temp()
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joules_out = self.conductance * deltaT # * 1 sec
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self.joulesAdded -= joules_out
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self.nextMedium.add(joules_out)
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print ("%.2f" % (self.temp(),)),
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self.nextMedium.simulate_losses()
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class Outside:
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def add(self,J): pass
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def temp(self): return 0
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def simulate_losses(self): print
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# going to need heat capacity in J/K also
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# .temp() .add(J) .simulate_losses()
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# try simulating 'unheated room before the outside' also ?
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# (or would that just factor into the insulation calcs)
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# 1000J/Kg/K
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# 1.225 kg/m3, 30 m3
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#simulate_heating_element(2000,49,50,Medium(20000,15,Medium(40000,200,Outside()))) # settles on 3.4 degrees ?? need more than 50? runs <50% of time (or is the 15 too small)
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#simulate_heating_element(2000,19,20,Medium(40000,200,Outside())) # stuck on 9.9
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# try better insulation to outside (for comparing heaters) :
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#simulate_heating_element(2000,49,50,Medium(20000,30,Medium(40000,100,Outside()))) # reaches 11.4, 1.34kWh
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#simulate_heating_element(2000,11,12,Medium(40000,100,Outside())) # same average for comparison, 1.24kWh
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#simulate_heating_element(2000,11.4,12.4,Medium(40000,100,Outside())) # same minimum, 1.27kWh, both better than oil ??
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# should assume 4deg hysteresis for simple thermostat? (needed for life expectancy of the heater)
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# (room thermostat's switching differential/hysteresis is typically 1C)
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#simulate_heating_element(2000,48,52,Medium(20000,30,Medium(40000,100,Outside()))) # 11.5/11.6, 1.34kWh
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#simulate_heating_element(2000,11.5,15.5,Medium(40000,100,Outside())) # same minimum = 1.47kWh (10% higher)
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#simulate_heating_element(2000,9.5,13.5,Medium(40000,100,Outside())) # same average = 1.22kWh (lower), but drops temp
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#simulate_heating_element(2500,48,52,Medium(20000,30,Medium(40000,200,Outside()))) # 1.5kWh consumed
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#simulate_heating_element(2000,6.5,10.5,Medium(40000,200,Outside())) # stuck on 9.9 anyway, 2kWh consumed (1500W=1.5kWh)
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#simulate_heating_element(2500,6.5,10.5,Medium(40000,200,Outside())) # 1.8kWh consumed (20% extra)
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#raise SystemExit
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import sys,os
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#sys.stdout = open("sim1.txt","w");simulate_heating_element(2000,48,52,Medium(20000,30,Medium(40000,100,Outside()))) # 11.5/11.6, 1.34kWh
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#sys.stdout = open("sim2.txt","w");simulate_heating_element(2000,11.5,15.5,Medium(40000,100,Outside())) # same minimum = 1.47kWh (10% higher)
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# try with worse insulation:
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# U-value = W/m2/K; if all brick, 2*2*(5*3+3*2+5*2)=124, divide by 10 if gd insulation (but NB effect of windows etc)
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sys.stdout = open("sim1.txt","w");simulate_heating_element(2500,48,52,Medium(20000,30,Medium(40000,200,Outside()))) # 1.51kWh
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sys.stdout = open("sim2.txt","w");simulate_heating_element(2500,6.5,10.5,Medium(40000,200,Outside())) # 1.81kWh (20% extra)
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sys.stdout = open("sim3.txt","w");simulate_heating_element(2500,26,31,Medium(20000,30,Medium(40000,100,Outside()))) # 0.82kWh (better insulation requires lower setting to get the 6.5C)
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sys.stdout = open("sim4.txt","w");simulate_heating_element(2500,6.5,10.5,Medium(40000,100,Outside())) # 0.9kWh (10% extra)
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sys.stdout = open("sim5.txt","w");simulate_heating_element(1250,26,31,Medium(20000,30,Medium(40000,100,Outside()))) # 0.77kWh (0.9kWh is now 17% extra with reduced element wattage)
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sys.stdout = open("sim6.txt","w");simulate_heating_element(2500,42,46,Medium(20000,30,Medium(10000,1000,Medium(30000,200,Outside())))) # back to bad insulation and only care about the air near the radiator (very rough simulation), slightly lower setting to get the 6.5C, 1.3kWh
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sys.stdout = open("sim7.txt","w");simulate_heating_element(2500,6.5,10.5,Medium(10000,1000,Medium(30000,200,Outside()))) # 1.52kWh = 17% extra
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# non-thermostat try (against sim6) :
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sys.stdout = open("sim8.txt","w");simulate_heating_element(400,65,105,Medium(10000,1000,Medium(30000,200,Outside())))
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sys.stdout = open("sim9.txt","w");simulate_heating_element(800,65,105,Medium(10000,1000,Medium(30000,200,Outside())))
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sys.stdout = open("sim10.txt","w");simulate_heating_element(1200,65,105,Medium(10000,1000,Medium(30000,200,Outside())))
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sys.stdout = open("sim11.txt","w");simulate_heating_element(2500,58,62,Medium(20000,30,Medium(10000,1000,Medium(30000,200,Outside()))),1240) # heat up to 9C near heater, 0.74kWh, >=6.5C between t=636 and t=1672
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sys.stdout = open("sim12.txt","w");simulate_heating_element(2500,42,46,Medium(20000,30,Medium(10000,1000,Medium(30000,200,Outside()))),1672) # for comparison (same heater at lower setting for longer, >=6.5 from 899 to 1752, 0.71kWh)
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sys.stdout = open("sim13.txt","w");simulate_heating_element(1200,65,105,Medium(10000,1000,Medium(30000,200,Outside())),2200) # 0.73kWh
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os.system("(echo 'set terminal png medium x000000 xffffff size 320,240 enhanced';echo \"set output 'oil1.png'\";echo 'set lmargin 0';echo 'set rmargin 0';echo 'set tmargin 0';echo 'set bmargin 0';echo 'set format x \"\"';echo 'set format y \"\"';echo 'set xrange [0:5400]';echo 'set yrange [0:55]';echo \"plot 'sim1.txt' using 1:2 title '' with lines,'sim1.txt' using 1:3 title '' with lines,'sim2.txt' using 1:2 title '' with lines\")|gnuplot")
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os.system("(echo 'set terminal png medium x000000 xffffff size 320,240 enhanced';echo \"set output 'oil2.png'\";echo 'set lmargin 0';echo 'set rmargin 0';echo 'set tmargin 0';echo 'set bmargin 0';echo 'set format x \"\"';echo 'set format y \"\"';echo 'set xrange [0:5400]';echo 'set yrange [0:55]';echo \"plot 'sim3.txt' using 1:2 title '' with lines,'sim3.txt' using 1:3 title '' with lines,'sim4.txt' using 1:2 title '' with lines\")|gnuplot")
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os.system("(echo 'set terminal png medium x000000 xffffff size 320,240 enhanced';echo \"set output 'oil3.png'\";echo 'set lmargin 0';echo 'set rmargin 0';echo 'set tmargin 0';echo 'set bmargin 0';echo 'set format x \"\"';echo 'set format y \"\"';echo 'set xrange [0:5400]';echo 'set yrange [0:20]';echo \"plot 'sim6.txt' using 1:3 title '' with lines,'sim6.txt' using 1:4 title '' with lines,'sim7.txt' using 1:2 title '' with lines,'sim7.txt' using 1:3 title '' with lines\")|gnuplot")
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os.system("(echo 'set terminal png medium x000000 xffffff size 320,240 enhanced';echo \"set output 'oil4.png'\";echo 'set lmargin 0';echo 'set rmargin 0';echo 'set tmargin 0';echo 'set bmargin 0';echo 'set format x \"\"';echo 'set format y \"\"';echo 'set xrange [0:5400]';echo 'set yrange [0:20]';echo \"plot 'sim6.txt' using 1:3 title '' with lines,'sim8.txt' using 1:2 title '' with lines,'sim9.txt' using 1:2 title '' with lines,'sim10.txt' using 1:2 title '' with lines\")|gnuplot")
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os.system("(echo 'set terminal png medium x000000 xffffff size 320,240 enhanced';echo \"set output 'oil5.png'\";echo 'set lmargin 0';echo 'set rmargin 0';echo 'set tmargin 0';echo 'set bmargin 0';echo 'set format x \"\"';echo 'set format y \"\"';echo 'set xrange [0:3000]';echo 'set yrange [0:10]';echo \"plot 'sim11.txt' using 1:3 title '' with lines,'sim12.txt' using 1:3 title '' with lines,'sim13.txt' using 1:3 title '' with lines\")|gnuplot")
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assert not os.system("test -e oil1.png && test -e oil2.png && test -e oil3.png && test -e oil4.png && test -e oil5.png"), "graph-plotting failed, check gnuplot"
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os.system("rm sim*.txt")
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print ("TODO: further compress the PNG files with advpng -4 -z (e.g. on srcf)")
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