MET 220 Lab 2 Solar Energy

Date: February 5, 2023 To: Bill Hutzel, Jiayu (George) Luo From: Mohammad Khokha Chaoyi Hu Marianna Broton Joseph Fischer Subject: Lab 02 – Solar Energy LAB REPORT SECTIONS & GRADING: Experiment Performance/Participation ______ / 11 Executive Summary ______ / 2 Technical Details Apparatus Sketch ______ / 2 Data Sheets ______ / 2 Results Tables/Graphs ______ / 2 Sample Calculations ______ / 2 Answers to Questions ______ / 2 Spelling/Grammar/Writing ______ / 2 TOTAL ______ / 25

Executive Summary: Experiment two was conducted over two lab sessions to as instructed. The first portion of the experiment was a tour of the solar energy collection systems in use on Knoy Hall. During the tour, the team took notes/pictures of key components in the system. After the tour, the team drew diagrams of the glycol and air solar collection systems. The second day started with data collection from a sample day (16 Jan, 2024). Variables identified such as panel area (A) Solar intensity (e) flow rate (V) and temperature (T, inlet and outlet) were used in Excel to calculate the efficiency (%). Equations like the samples provided were added to the data sheet. An Excel spreadsheet was used to calculate the percent efficiency and solar energy factor of the various solar panel designs. Each design was ranked by their perspective efficiency from 1-8 (1 being most efficient) before and after the calculations were made. The most efficient design tested in this lab was the commercial glycol heat pipe. Even with a relatively low surface area, the pipe design with vacuum insulation allowed for more reflections to take place effective collection of solar energy than the other designs. The least efficient design was the black air surface flat plate. This design was to make a larger surface area simple yet not effective when compared to its competition. Compared with Air Black Surface Flat Plate the design of increasing area corrugated the surface didn’t help. These results indicate the correlation between design, function, and efficiency when collecting solar energy.

3 Glycol Black Surface No Fins Black surface with tubes lining the surface which transfer heat to glycol. 4 Glycol Copper Surface No Fins Uses a copper surface with copper tubes to transfer heat to glycol. 5 Glycol Black Surface Finned Tubes Black tubes with heatsink- like fins to further trap heat to transfer to glycol.

6 Air Black Surface Flat Plate Just a flat plate over which air flows and is heated by the sun. 7 Air Black Surface Perforated X This has perforated Xs to increase the efficiency by increasing surface area of the collector. 8 Air Black Surface Corrugated Plate This has a corrugated back plate to increase the efficiency by increasing surface area of the collector.

1 Glycol Commercial Heat Pipe 1.28 N/A gpm 84.4 109.8 2 Glycol Commercial Flat Plate 2.489 53 gpm 84.4 109.8 3 Glycol Flat Black Surface 1.604 53 gpm 84.4 109.8 4 Glycol Copper Surface No Fins 1.604 53 gpm 84.4 109.8 5 Glycol Black Surface Finned Tubes 1.604 53 gpm 84.4 109.8 6 Air Black Surface Flat Plate 1.604 53 cfm 54.7 91 7 Air Peforated X Perforated Plate 1.604 53 cfm 54.7 91 8 Air Black Surface Corrugated Plate 1.604 53 cfm 54.7 91 SOLAR PANEL DESCRIPTION SOLAR PANEL PERFORMANCE # Panel Description Estimated Rank 1 to 8 Panel Area (m 2 ) Solar Power Available (Btu/h) Mass Flow Rate (lbm/h) Solar Power Collected (Btu/h) Efficiency (%) Actual Rank 1 to 8

1 Glycol Commercia l Heat Pipe 1 1.28 4338.568 31.824 6411.323 147.7 1 2 Glycol Commercia l Flat Plate 2 2.489 8436.478 31.834 6411.323 75.99 5 3 Glycol Flat Black Surface 5 1.604 5436.767 32.406 6539.55 120.13 2 4 Glycol Copper Surface No Fins 6 1.604 5436.767 28.64 5770.191 106.13 4 5 Glycol Black Surface Finned Tubes 3 1.604 5436.767 31.824 6411.323 117.925 3 6 Air Black Surface Flat Plate 8 1.604 5436.767 144.114 1255.521 23.09 7 7 Air Peforated X Perforated Plate 7 1.604 5436.767 163.37 1423.295 26.18 6 8 Air Black Surface Corrugated Plate 4 1.604 5438.767 172.96 1506.79 17.71 8 Table 4. Summary of solar energy factor for solar thermal panels SOLAR PANEL DESCRIPTION

DISCUSSION QUESTIONS:

1. Compare the two performance parameters (efficiency and energy factor) for the collectors. Explain the similarities/differences between these two terms. Which is more important for evaluating solar collector performance? The efficiency parameter considers the heat collected and the sun intensity available, and this shows how well the solar heat panel is able to take heat from the sunlight and use it to heat a fluid to use for various purposes. The energy factor considers the head collected and the electricity used to run the fluid through the collector. The main difference is the value is much higher for the energy factor as for these panels it does not take much energy, relatively speaking, to run the fluid through these systems as compared to the energy from the sun that these collectors collect. However, the efficiency of these panels is limited to being less than 100% so that means that there is an upper limit for efficiencies that doesn’t exist for solar energy factor. The more important factor for solar collector performance is efficiency because the more energy that the collector is able to use out of a given amount of sunlight, the better that solar collector is at taking energy from the sun and being able to use it. Solar energy factor does not deal with the energy lost in the collector as well as efficiency clearly illustrates. 2. Compare the overall performance of the air collectors to the glycol collectors. Which fluid (air or glycol/water) is better at transferring heat? Consider both efficiency and energy factor and use specific numbers to justify your answer. The glycol/water mixture is better at transferring heat than air. The efficiencies are, overall, much higher with many of the values ranging over 100% using glycol/water mixtures rather than air with the highest efficiency being 147.7%. Using air only brings efficiency up to 26.18% using the perforated X panel. The other two are below this value. As you can see from the tables, the glycol mixtures have a higher SEF than the air panels which means more heat is conducted through these panels. 3. Compare the overall performance of the two glycol collectors that were purchased from an outside vendor to the other three collectors that were fabricated at Purdue. Is it worthwhile to purchase a collector or is it better to make your own? Consider both efficiency and energy factor and use specific numbers to justify your answer. According to the data from the lab, the difference in performance between the Purdue-made collectors and the collectors purchased from outside sources were all above 75%. The flat plate collector bought from an external vendor has an efficiency of 75.99% which was the lowest of any glycol collector. The efficiencies of the Purdue-made panels were all above the flat-plate collector and were within 12 percent of each other but had lower efficiencies when compared to the Evacuated Tube Heat collector. The Evacuated Tube Heat collector had the highest efficiency, so for projects with large budgets, it may be useful to buy high efficiency solar collectors, like the evacuated tube heat collector, as opposed to making heat collectors in-house. 4. Look at the features (e.g. size, color, material, etc.) of all eight collectors. Are there any general characteristics that tend to improve solar collector performance?

References: AEL Building Automation System (BAS) Knoy Hall –Solar –Thermal