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1. ### 海水化淡來發電?!

... low-potential termal energy of any surrounding environment such as solar radiation , hot sand, warm seawater, thermal ground water etc. The obtained...

From Part (a): dQ/dt = 4εσ(Tw)^3(Tw-T) Since dQ = Cp.dT dQ/dt = Cp.(dT/dt) Hence, Cp.(dT/dt) = 4εσ(Tw)^3(Tw-T) dT/(Tw - T) = (4...

3. ### Physics heat

...e.g. water, air) is a medium for convection to take place. 2. Infrared radiation is commonly known heat-rays. It is a means...

... the speed of electromagentic wave be 3 x 10^8 m/s Hence, frequency of radiation = 3x10^8/(3/100) Hz = 10^10 Hz = 10 billion Hz 2014-07-24 17...

6. ### phy energy

1. For a fixed voltage V, the power P consumed by the lamp, of resistance R, is given by, P = V^2/R An increase in resistance R of the lamp leads to a decrease of power P, and vice versa. 2. It...

7. ### Heat transfer

...of the sleeping bag. Hence, by Stefan's Law on radiation , 97 = (5.67 x 10^-8).(2).T^4 where the constant (5.67 x 10^-8 w/m^2....

8. ### conduction and convection

(b)(i) Original conductance of wall = 0.865/0.23 w/m^2.K = 3.761 w/m^2.K Resistance of composite wall = (0.23/0.865 + 0.23/0.26) K.m^2/w = 1.151 K.m^2/w Conductance of composite wall = 1/1.151 w/m^2.K = 0.8692 w/m^2.K Reduction in heat flow = [(3...

9. ### Thermal phys: heat flow

Thermal conductivity of composite wall B and C = (1 x 1.5 + 1.8 x 0.8)/(1+1.8) w/m^2.K = 1.05 w/m.K Resistance of composite wall B and C = 1.2/1.05 m^2.K/w = 1.143 m^2K/w Resistance of wall A = 0.8/0.6 m^2K/w = 1.333 m...

10. ### heat transfer

... (2)(i) New emissivity (輻射率) = 0.9 x 0.8 = 0.72 hence, intensity of radiation = 0.72 x (5.7x10^-8) x (273+25)^4 W/m^2 = 324 W/m^2 Original...