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lmb147铜虫 (正式写手)
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[求助]
急需、谢谢
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at the appropriate values for inlet temperature and flow rate until they remain constant within ±2% or ±1.0°C (1.8°F) and ±0.005 gpm (0.000315 L/s), whichever is greater, respectively, for 15 minutes prior to each period in which data will be taken to calculate the efficiency values. Also, the ambient temperature shall vary by no more than ±1.5°C (2.7°F) during this same time interval.When an indoor solar irradiance simulator is employed and true steady-state conditions can be obtained, the time interval specified above is not applicable.A steady-state condition is assumed to exist when the outlet temperature of the fluid varies less than 0.05°C (0.09°F)per minute. 8.3.3.4 Check for Dust and Moisture. The surface of the collector cover plate as well as exposed envelopes of the pyranometer(s) and pyrheliometer shall be wiped clean and dry prior to the test period(s). If local pollution or dust has formed a deposit on the transparent surfaces, the wiping should be carried out very gently, preferably after blowing off most of the loose material or after wetting it, in order to prevent scratching of the surface. This is particularly important for the solar radiation-measuring instruments, since such abrasive action can appreciably alter the original transmission properties of the enclosing envelope.The pyranometer(s) shall be checked prior to testing to see if there is any accumulation of water vapor enclosed within the glass cover. The use of wet pyranometers (where moisture is visible) shall not be |
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