http://hdl.handle.net/11189/1912 2026-08-12T13:34:57Z http://hdl.handle.net/11189/10670 Title: The question of thermoelectric devices (TEDs) in/efficiency - a practical examination considering thermoelectric coolers (TECs) Authors: BAYENDANG, NGANYANG PAUL; Balyan, Vipin; Kahn, Mohamed Tariq Ekeramodien Abstract: Thermoelectric devices (TEDs) are clean energy devices with diverse applications; however, the question of their energy in/efficiency and how to improve it, has been a subject of research/debate among many researchers and non/users. In an effort to contribute to this quest/scientific discourse, this paper focuses on energy in/efficiency in TEDs when operated as thermoelectric coolers (TECs) for cooling purposes. A practical research was performed using sixteen identical TECs operated in the same performance test conditions and powered in turns using 12 V, 10 V, 8 V, 6 V and 4 V, with a 5 A current limit, to investigate TECs in/efficiency inconsistency. It was found that the TECs (TEC-12706 from the same manufacturer) used in the study all performed differently under identical test setup; however, they all performed optimally at 8 V, with the best (TEC3) attaining a cooling of −4.81 °C with an input power of 21.09 W and the worst (TEC9) attaining a cooling of 12.63 °C with a power input of 45.52 W. From our findings, TECs in/efficiency can therefore be summarily attributed to five fundamental factors and though TECs efficiency is well known to be limited by 1) its intrinsic p-n junction semiconductor chemistry and physics at materials level; however, we can conclude that given the same semiconductor technology, TEC inefficiency is further exacerbated by 2) low-quality manufacturing/assembly at module level, 3) inadequate designs at application/system level, 4) substandard system construction/workmanship at implementation level and 5) general lack of theoretical/physical knowledge of TECs operation at users’ level. 2025-01-01T00:00:00Z http://hdl.handle.net/11189/10669 Title: The principles of energy conservation by managing facility voltage levels and reactive power flow Authors: Ngongo, Prosper Kabasele; Almaktoof, Ali; Kahn, Mohamed Tariq Ekeramodien Abstract: Reactive power optimization and voltage control are essential for the efficient operation of power systems. Effective management of these factors reduces energy losses and improves both economic performance and system security. In South Africa, the nominal phase voltage level is set at 220V, with an allowable range between 209V and 231V (±5 %). To ensure that the supply voltage stays within this acceptable range, the grid often provides a voltage higher than the nominal 220V at which most electrical equipment is designed to operate. Consequently, the equipment consumes more power without any improvement in performance. Additionally, while the grid supplies both real and reactive power, only the real power consumed is billed. To address the cost of unbillable reactive power, a power factor penalty is implemented. The practice of controlling supply voltage levels and enhancing the power factor is known as volt-var optimization. This approach involves regulating voltage levels and reactive power to maximize energy efficiency. This paper employs a model-based Volt-var optimization technique to illustrate how facilities can reduce energy waste. The findings indicate that, for facility system losses estimated at 5 %, reducing the useable voltage from 400V nominal to 380V can achieve a percentage loss reduction of 0.487 %. This saving is directly proportional to the difference between the useable and nominal voltages. Furthermore, optimizing the power factor from 0.85 lagging to unity results in a percentage loss reduction of 1.388 %. This saving is indirectly proportional to how closely the inherent power factor approaches unity. 2025-01-01T00:00:00Z http://hdl.handle.net/11189/10668 Title: The question of thermoelectric devices (TEDs) in/efficiency - a practical research considering thermoelectric generators (TEGs) Authors: BAYENDANG, NGANYANG PAUL; Balyan, Vipin; Kahn, Mohamed Tariq Ekeramodien Abstract: Thermoelectricity is a versatile clean energy technology; however, its in/efficiency has been a question of debate. Thus, this practical study focuses on thermoelectric devices' (TEDs') performance when operated as thermoelectric generators (TEGs). Sixteen identical TEDs (TEC-12706 of the same made and model) were operated as TEGs under the same experimental setup and test modalities with a hotside temperature between ∼20°C and ∼100°C and a coldside temperature of ∼20°C, to practically and comparatively examine the TEGs voltage production and energy conversion in/efficiency. The findings revealed that, while it's already common knowledge that a TEG output voltage is proportional to its temperature difference as evident in all the TEGs used in the study; however, as the TEGs temperature difference proportionally increases, some of the TEGs relatively produced less, the same and more output voltages at certain temperature differences compared to others. For example, TEG1 and TEG3 produced almost the same output voltages throughout; however, at ∼100°C hotside temperature, TEG3 produced 3.16 V, whereas TEG1 produced 2.90 V. While such widespread TEGs discrepancies can be mostly attributed to bad manufacturing/poor workmanship, they are usually misconstrued by some as a generic inherent thermoelectricity technology limitations which this study highlights. 2025-01-01T00:00:00Z http://hdl.handle.net/11189/10667 Title: The Question of Thermoelectric Devices (TEDs) in/efficiency - a practical investigation considering Thermoelectric Heaters (TEHs) Authors: Bayendang, Nganyang Paul; Kahn, Mohamed Tariq Ekeramodien; Balyan, Vipin Abstract: Thermoelectricity is a promising technology; however, though clean and versatile, its efficiency has been questionable and consequently limiting its extensive utilization. Many published research on thermoelectricity have been on power generation and cooling applications, with few publications on heating, especially practically. Thus, this article practically focuses on thermoelectric devices (TEDs) when used as thermoelectric heaters (TEHs). Sixteen identical TEDs (TEC-12706) were operated as TEHs under similar test modalities and powered in succession with 12, 10, 8, 6, and 4 V, to practically examine TEHs energy dynamics and in/efficiency. It was found that all the TEHs used in the research performed relatively inconsistent with each other with the worst-performed TEH (TEH0) having a mean hot-side temperature of 30.276°C with a mean power consumption of 13.826 W; whereas the best-performed TEH (TEH3) had a mean hot-side temperature of 40.4°C with a mean power consumption of 20.822 W. Furthermore, all the TEHs hot-side temperature increased proportionately with the input voltage; though at the specified voltages, the TEHs hot-side temperature increased while its input power decreased over time. The concepts of TEH hot-side mean temperature and TEH mean input power were also introduced. 2025-01-01T00:00:00Z