Conditions for 9th options:
In the first problem: n = 323 Fg, m2 = 40 t, o C = 520
In the second problem: N, MW = 2 t1, oC = 21 t2, ° C = 4
The third problem: h, km = 0,6 z, km = 3,5 (dT / dz), ° C / km = 35
The fourth problem: n = 6 η = 0,6
The fifth problem: Q, GJ = 0,60 t1, oC = 52 t2, ° C = 28
The sixth problem: F, = 3500 km2 R Wed, m = 5.2
The seventh problem: n = 3 m = 40
In the solar power tower is set n heliostats ka¬zhdy of which has a surface Fg m2. Heliostats reflect the sun's rays onto a receiver at the surface in which the registered maximum illumination energetiche¬skaya H ave = 2.5 mW / mg. The reflection coefficient of the heliostat Rg = 0.8. the absorption coefficient of the receiver in April = 0.95. Maximum obluchen¬nost heliostat mirror collar nut = 600 W / mg.
Determine the surface area of \u200b\u200bthe receiver Fpr and thermal losses it caused by radiation and convection when the working temperature of the coolant so¬stavlyaet t ° C. Degree black receiver APW = 0.95. Convective loss of half the losses from radiation.
It is believed that the actual efficiency η oceanic thermal power plants (OTPP), which uses the temperature difference of surface and deep water (T1 - T2) = ΔT and rabo¬tayuschey Rankine cycle, half the thermal efficiency of the plant, which operates on the Carnot cycle, ηtk. Assess the possible magnitude of the actual efficiency of the OTPP, ra¬bochim body which is ammonia, if the water temperature on the surface of the ocean t, ° C, and the water temperature of the ocean at a depth t2, ° C. What is the flow of warm water V, m / h required for OTPP N MW capacity?
Assume that the density of water ρ = 1 • 103 kg / m3 and a specific mass teploem¬kost Cp = 4,2 • 103 J / (kg-K).
Determine the initial temperature t2 and the amount of geothermal energy
EO (J.), aquifer thickness h km at a depth of z km if asked characterized the formation rock-tics:
RGR density = 2700 kg / m3;
porosity a = 5%;
SGR = specific heat capacity of 840 J / (kg • K).
The temperature gradient (dT / dz) in ° C / km to select options on the table setting. Avg-nyuyu surface temperature to be set equal to 10 ° C. Specific tep¬loemkost water St = 4200 J / (kg • K); ρ = density of water 1 • 103 kg / m3.
Calculation produce relative to the surface area F = 1 km2. The minimum temperature of the reservoir dopusti¬muyu take equal t1 = 40 ° C
Determine also the time constant extraction of heat energy τo (s)
when pumping the water into the reservoir and discharge its V = 0,1 m3 / (s • km2). What will teplo¬vaya power Remove the original (dE / dz) τ = 0 and 10 years (dE / dz) τ = 10?
Determine the volume Vb biogazogeneratora and daily biogas output Vr in usta¬novke dispose of manure from cows n and provides its thermal power N (W). The cycle time of fermentation τ = 14 days at a temperature t = 25 ° C; supply of dry-fermented direct material from one animal is at a rate of W = 2 kg / day; biogas from dry weight νg = 0.24 m3 / kg. The methane content in biogas is 70%. The efficiency of the burner mouth-tron devices η. Density dry mate¬riala distributed in bulk biogazogeneratora p ≈50 dry kg / mg. Heat sgora¬niya methane under normal physical conditions Qnr = 28 MJ / m3.