Q2. What are the main factors that influence the thermal performance of the collector?
The main factors that influence the thermal performance of the collector include solar intensity, 359 ambient temperature, evaporation temperature, and thermal resistance of the PHP absorber.
Q3. Why was the first rapid drop in temperature observed at the start-up stage?
The first rapid drop in temperature was observed at the 279 start-up stage because of the opening of the glass cover to check the thermocouples.
Q4. How is the end of the solar absorber?
The ending time 277 of the PHP absorber is approximately 2:00 PM, and the ending temperature of the evaporation 278 section is about 75 °C (similar to startup).
Q5. What is the effect of the CPC on the thermal efficiency of the solar collector?
421 2) The thermal resistance of the PHP absorber decreases with the increase in ambient temperature, 422 solar intensity, and evaporation temperature which is found to be the main factor that affects the 423 thermal efficiency of the collector and can reach nearly 0.26 °C/W. 424 3) The experimental results suggest that the heat flux of the PHP absorber’s evaporation section 425 concentrated by CPC with a concentration ratio of 3.4 is appropriate and the use of CPC is 426 reasonable.
Q6. What is the main factor that influences the thermal efficiency of the solar collector?
The reason is that the thermal resistance of the 391 PHP-absorber, which is the main factor influencing the thermal efficiency of the collector, decreases 392 with the increase in solar irradiation intensity and evaporation temperature (see Fig.7(c)).
Q7. What is the main factor that influences the thermal performance of the solar collector?
In consideration of the solar energy input, heat loss, and heat 372 collection, the thermal performance of the collector increases with the increase in evaporation 373 temperature and the decrease in the thermal resistance of the PHP absorber is the main factor that 374 influences its thermal performance, as shown in Fig. 9 (d). 375 376 (a) (b) 377 378 (c) (d) 379 380 Fig.
Q8. How can the thermal performance of the solar collector be improved?
352 Furthermore, the thermal performance of the collector can be improved by increasing the reflective 353 ratio of the reflective film and absorption coating efficiency and reducing the heat loss of the glass 354 cover.
Q9. What is the definition of the instantaneous heat collecting efficiency of the solar collector?
The instantaneous heat collecting efficiency of the solar collector is defined as the ratio of the 228 heat absorbed by water to the total solar irradiation reached to the solar collector.
Q10. What is the main factor influencing the thermal efficiency of the solar collector?
Figure 9 (c) shows that the efficiency of the collector 368 increases with the increase in evaporation temperature because the thermal resistance of the PHP 369 absorber is lower at a higher evaporation temperature.
Q11. What are the three stages of the solar collector?
the operation of the solar collector appears three 264 working stages, namely, start-up, steady state, and shutdown corresponding to the level of solar 265 intensity.
Q12. How many uncertainties of the water flow rate and solar irradiation intensity are there?
The 235 uncertainties of the water flow rate and solar irradiation intensity are 2.5% of the measuring range 236 (±1.5L/h) and ±10 W/m2, respectively.
Q13. Why is the thermal efficiency of the solar collector higher than those in literatures?
The (Tp-Ta)/I values of the present work are 386 higher than those in literatures [25] and [37] due to the solar concentration by CPC.