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	   "source": [
       "# Chapter 12: Flywheel Energy storage"
	   ]
	},
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		   "metadata": {},
		   "source": [
			"## Example 12.1: Compressed_air_temperature.sce"
		   ]
		  },
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"source": [
"clc\n",
"clear\n",
"//Input data\n",
"V=64000//Volume in m^3\n",
"Q=8300//Discharge in m^3/hr\n",
"p1=1//Pressure in bar\n",
"T1=20+273//Temperature in K\n",
"p2=100//Pressure in bar\n",
"pn=70//Polytropic efficiency in percent\n",
"pt=60//Peaking turbine efficiency in percent\n",
"g=1.4//Ratio of specific heats\n",
"cp=1.005//Specific heat in kJ/kg.K\n",
"R=0.287//Gas constant in kJ/kg.K\n",
"\n",
"//Calculations\n",
"T2sT1=(p2/p1)^((g-1)/g)//Temperature ratio \n",
"T2s=(T1*T2sT1)//Temperature in K\n",
"T21=(T2s-T1)/(pn/100)//Difference in Temperatures in K\n",
"T2=(T21+T1)-273//Temperature in degree C\n",
"v=(R*T1)/(p2*100)//Specific volume in m^3/kg\n",
"mf=(Q/(v*3600))//Mass flow rate in kg/s\n",
"E=(mf*cp*T21)/1000//Rate of energy storage in MW\n",
"t=(V/Q)//Storage time in hour\n",
"tE=(E*t)//Total energy storage in MWh\n",
"Ed=(tE*(pt/100))//Total energy delivered by the peaking turbine in MWh\n",
"\n",
"//Output\n",
"printf('(a) the compressed sir temperature is %3.0f degree C \n (b) the storage time is %3.2f hour \n (c) the total energy storage is %3.0f MWh \n (d) the total energy delivered by the peaking turbine is %3.0f MWh',T2,t,tE,Ed)"
   ]
   }
,
{
		   "cell_type": "markdown",
		   "metadata": {},
		   "source": [
			"## Example 12.2: Storage_time.sce"
		   ]
		  },
  {
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	   "execution_count": null,
	   "metadata": {
	    "collapsed": true
	   },
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"source": [
"clc\n",
"clear\n",
"//Input data\n",
"V=175000//Volume in m^3\n",
"d=4//Diameter in m\n",
"U=1.5//Overall heat transfer coefficient in W/m^2.K\n",
"p2=2//Pressure in bar\n",
"p1=20//Pressure in bar\n",
"Ta=20//Ambient temperature in degree C\n",
"cp=4.35//Specific heta of water in kJ/kg.K\n",
"e=96//Efficiency in percent\n",
"ppe=25//Peaking plant efficiency in percent\n",
"\n",
"//Calculations\n",
"//At 20 bar\n",
"T1=212.37//Saturation temperature in degree C\n",
"hf1=908.5//Enthalpy in kJ/kg\n",
"vf1=0.0011766//Specific volume in m^3/kg\n",
"//At 2 bar\n",
"T2=120.23//Saturation temperature in degree C\n",
"hf2=504.8//Enthalpy in kJ/kg\n",
"vf2=0.0010605//Specific volume in m^3/kg\n",
"ad=(1/2)*((1/vf1)+(1/vf2))//Average density of water in kg/m^3\n",
"tc=(d*ad*cp*1000)/(4*U*3600)//Time constant in h\n",
"ts=(log(1/(1-((1-((e/100)))/((T1-Ta)/(T1-T2))))))*tc//Storage time in h\n",
"m=(V/vf1)//Mass of water needed in kg\n",
"E=(m*(hf1-hf2))/(3600*10^3)//Total energy stored in MWh\n",
"Ed=(E*(e/100)*(ppe/100))//Energy delivered in MWh\n",
"\n",
"//Output\n",
"printf('(a) the storage time is %3.3f h \n (b) the total energy stored in the accumulator is %3.1f MWh \n (c) the total energy that can be delivered by the peaking turbine is %3.2f MWh',ts,E,Ed)"
   ]
   }
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