Radiation Heat Transfer Lab

The objective of this research laboratoryoratory look into is to investigate the light beam rectitudes (Lamberts blank, cos lettuce police force and Stefan-Boltzmann fairness) using thermal and optical radiation.This look into was carried out with the assistance of the Thermal Radiation Apparatus which consists of a heat cite (that supplys the heat for the verification of the Stefan-Boltzmann Law), a thermopile (that assists in detecting the temperature), a luxmeter (that assists in bar the luminous intensity for the verification of Lamberts keep & romaine Law), absorption plates that detect any gleam hazard upon them, a swivelling light ancestry (that assists in provides luminous radiation for the verification of Lamberts Cosine Law) and finally cadence amplifier that detects he amount of irradiance incident upon the measuring rod plates and provides an electronic output in the form of a reading.Lamberts Distance Law states the as the breakup distance surrounded b y the point source of radiation and the detector plates is increased, the irradiance notice leave behind decrease. This law was proved to be precise since the irradiance and the distance have a negative toss of -1.584 on Figure 1.Lamberts Cosine Law, which constitutes that the radiant intensity, I, of the radiation emitted by a flat source is analogous from any direction but the irradiance, E, decreases with the increase of cosine of the angle of incidence. This law was also proved to be accurate as it can be seen from elude 2 that as the angle of incidence increased, the irradiance decreased.The Stefan-Boltzmann Law was also verified. It was observed that the irradiance of a blackbody was proportionate to the fourth business collide withice of the absolute temperature.The main source erroneousness in the lab examine was that the laboratory room was not tout ensemble dark and caused the measuring plates to detect ambient light radiation and giving untrue readings.PROCEDURE The procedure outlaid in the lab manual was followed to precision. The procedure steps were carried out in a safe manner for Lamberts Distance Law, Lamberts Cosine Law and Stefan-Boltzmann Law. 2RESULTSLamberts Distance LawPlease interrelate to Table 1, Figure 1 and Figure 2 in Appendix A Tables and Figures for the Results of the experiment conducted to observe Lamberts Distance Law.Lamberts Cosine LawPlease refer to Table 2, Table 3, Figure 3 and Figure 4 in Appendix A Tables and Figures for the Results of the experiment conducted to observe Lamberts Cosine Law.Stefan-Boltzmann LawPlease refer to Table 4, Table 5 and Figure 5 in Appendix A Tables and Figures for the Results of the experiment conducted to observe Stefan-Boltzmann Law.DISCUSSIONLamberts Distance LawTheoretically it is believed that Lamberts Distance Law correlates to the detail that the irradiance of the radiation emitted perpendicularly towards a locate from a point source is inversely proportional to the squ are of the distance separating the illuminated surface and the source. 2 From the experiment it was observed that as the distance between the illuminated surface and the source of radiation increased, the irradiance decreased as an individual can notice that at a separation distance of 100 mm the irradiance was observed to be 1069 W/m2 and at the separation distance of 800 mm the irradiance reduced to a 126 W/m2. From Figure 1 (Lamberts Distance Law plot on a Log-Log scale) and Figure 2 (Lamberts Distance Law plotted on a frequent scale), it can be discerned that the irradiance diminishes as the separation distance between the source of radiation and the illumination surface increases.Lamberts Cosine LawLamberts Cosine Law states that the radiant intensity, I, emitted by a flat source is the analogous from any direction, however the irradiance, E, decreases with the cosine of the angle of direction. 2 This law essentially dictates that the direction of illuminance is irrelevant si nce the radiance from the surface at any angle is exactly the same to the human eye this happens due to the fact that as the angle of direction of the rays increases relative to the normal (0 angle of direction), the area of incidence for the radiation decreases. another(prenominal) theoretical observation that can be made from the law stated above is that the maximum irradiance will occur at the angle of zero degrees.It can be perceived from Figure 3, in which the consanguinity between angle and light intensity on blackbody in a radian mensurate is shown, the blue circles represent the angle from the center of the unit circle that correspond to the respective normalized illuminance value. From Table 2 it can be noted that as the angle of incidence is increased the illuminance decreases this corroborates Lamberts Cosine Law even further.Stefan-Boltzmann LawThis law situates that the total irradiance of a blackbody radiator is proportional to the fourth power of the absolute tempe rature. 1 This can be stated mathematically, as , where ? is the Boltzmann constant with a value of 5.67*10-8 W/m2*K4 although this law applies solely to blackbodies. From Figure 4 it can observed that a linear relationship develops between the temperature and the irradiance, with a positive slope of 2078.1 when the temperature climbs the measuring amplifier detects a higher amount of irradiance.The theoretical irradiance determine were calculated, since the only protean parameters in the equation for the irradiance are the temperatures that are detected. From Table 5 it can be discerned that the theoretical values had a share error of approximately 76% when compared to the experimental values. This is a very high percent error and can be explained by that fact that not all of the radiation emitted by the source reaches the measuring plates and the majority of the radiation is lost to the environment.ErrorsThe main source error in the lab experiment was confronted during the sec ond part of the lab during which the Cosine Law was being detected. This room needs to be completely dark and only the radiance from the source must reach the measuring plates so as to provide the most accurate results. This was not achieved as the room was not completely dark and ambient radiation was allowed to be incident upon the measuring plates causing an error.Experimental errors were caused due to the measuring ruler for the distances of separation and the error in the readings for the irradiance.Another source of error may be that all sources of radiance during the lab experiment were assumed to be point sources this is untrue as radiance was incident upon the measuring plates from reflection off the surfaces present in the laboratory room.CONCLUSIONFrom the laboratory experiment conducted the Lamberts Distance Law was proved to be true as it was observed that an inversely proportional relationship developed between the distance and the irradiance detected by the measuring amplifier. Similarly, the Cosine Law was also proved to be correct, as an inversely proportional relationship was also detected between the angle of incidence and the illuminance measured. The last law to be confirmed was the Stefan-Boltzmann Law, which was observed when the total irradiance of the blackbody radiator was proportional to the fourth power of the absolute temperature.Overall a firm understanding of Lamberts Distance & Cosine Laws and Stefan-Boltzmann Law and radiation transfer were gained.