Renewable energy in agro-industrial complex: Parameters of the wind power systems for heat production, storage and supply of green houses. Part 1

Table 4.2 lists the parameters of wind and traditional systems for heat supply on the organic fuel of various capacity, designed for the following initial data: area of the greenhouses is 10000…100000 m2; specific heat losses in the greenhouses are 200 W/m2; the specific power of electric system of additional illumination of plants – 100 W/m2; the average daily duration of the wind is 10 hours; the duration of the cold season is 6 months; average wind speed for a given region is 7 m/s; energy conversion efficiency of wind power system – 0,9; specific heat capacity of coolant (water) is 4,2 kJ/(kg x K); working temperature mode of operation for thermal storage unit – 200C…700C…200C; energy conversion efficiency of boiler on the organic fuel is 0.9; specific heat of combustion for fossil fuel (natural gas) is 32,7 MJ/m3.

 

The examples of energy parameters calculation for wind and gaseous power systems for heat supply of green house with area of 10000 m2

 

Thermal parameters of green house: Heat lossesintensity for 1 m2 area of building - 200 W = 200 J/s. Specific heat losses of 1 m2 area per 1 s - 200 (J/s)m-2 = 200 J = 200Jх0,24 calхJ-1 = 48 cal. Specific heat losses of 1 m2 area during 1 hour - 200(W/m2) х 3600 s = 720 kJ = 720 kJ х 0,24 (kcal/kJ) = 172,8 kcal; Specific heat losses per day - 720 kJх24 = 17,28 MJ = 17,28 MJ х 0,24 МcalJ = 4,15 Мcal.  Specific heat losses during a month - 17,28 MJ х 30 = 518,4 МJ = 518,4 МJ х 0,24 МcalJ = 124,4 Мcal; Specific heat losses during 6 months of heating season - 518,4 МJ х 6 = 3110 МJ = 3110 МJ х 0,24 (МcalJ) = 746,5 Мcal; Total heat losses of building during a day – 10000 m2х 17,28 МJ = 172,8 ГJ = 172,8 ГJ х 0,24 (ГcalJ) = 41,47 Гcal; Heat losses’ intensity for all area of green house building(s) – 200 (J/s) х m-2 х 10000 m2 = 2 МW. Average power for heat supply – 2 МW.

 

Wind power: Average power of wind turbine at duration of wind 10 hours per day is (2 МW х 24 h)/10 h = 4,8 МW. Average wind power that fall on 1 m2 area, perpendicular to wind flow direction and wind velocity of 7 m/s per 1 s is 0,5 х 1,2(kg/m3) х 73 (m/s)3 х 1 m2 = 206 J = 206 J х 0,24 cal/J = 50 cal. Specific WPT power is 206 W. During an hour 1 m2 of useful wind flow area produces 0,206 kWh = 0,206 kWh х 860 kcal/kWh = 177 kcal. During a day – 10 х 0,206 kWh = 2,06 kWh = 2,06 kWh х 3,6 МJ = 7,4 МJ = 7,4 МJ х 0,24 (МcalJ) = 1,78 Мcal. Area of wind flow cross section А, that provides power of 4,8 МW is 4,8(МJ/s)/[0,5 х 1,2 (kJ/m3) х 73(m/s)3] = 23301 m2. Wind flow with the area of cross section of 23301 m2 can be taken, for example, with 2 wind turbines (every one takes of 11660 m2 and has length of turbines blades of 60 m.

Heat accumulator: Heat quantity, stored by 1 m3 volume of water with a specific heat capacity 4,2 kJ/(kg·°C) when heating from 200C to 700C is 4,2 kJ/(kg·°C) х 50·°C = 210 MJхm-3; volume of water with a specific heat capacity 4,2 kJ/(kgх°C) that provides accumulation of 172,8 GJ per day is 172,8 GJ/0,210 GJхm-3 = 823 m3.

 

By Vasil Sidorov on October 15, 2012

Technopark QUELTA, Queltanews from

Nizhyn Laboratories of Scanning Devices

sidorovvasil@gmail.com

 

 


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