Browsing by Author "Purvee, Ariunbolor, Ph.D."

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    Technical and Economic Feasibility Study of Electrifying Coal Transportation: A Case Study of Tavan Tolgoi–Gashuun Sukhait
    (German-Mongolian Institute for Resources and Technology, 2026) Amgalanbaatar, Enkhjin; Purvee, Ariunbolor, Ph.D.; Enkhbold, Bold, MSc.
    The Tavan Tolgoi–Gashuun Sukhait (TT–GS) corridor is one of Mongolia's most critical coal export routes, spanning approximately 250 km from the Tavan Tolgoi coking coal mine in the South Gobi to the Gashuun Sukhait border crossing with China. Currently, this corridor depends almost exclusively on fleets of diesel-powered heavy-duty trucks, resulting in high fuel costs, substantial CO2, NOx, and particulate matter (PM) emissions, severe road wear from high axle loads, and logistical inefficiency. Mongolia's commitments under its Nationally Determined Contribution (NDC) to the UNFCCC mandate significant reductions in transport-sector emissions, making electrification of the heavy freight fleet a strategic priority. This thesis presents a preliminary technical and economic feasibility study evaluating the CR130EVT wide-body dual-trailer heavy-duty vehicle — available in a pure electric variant (783 kWh lithium-ion battery, 600 kW rated / 900 kW peak powertrain) and a diesel-electric hybrid variant (≥170 kWh battery plus 400 kW diesel engine) — for deployment on the TT–GS coal transport corridor. The study is structured around five analytical dimensions: (1) vehicle technical specifications and platform design; (2) axle loading mechanics and road infrastructure requirements; (3) multi-axle powertrain, electrical system, and control architecture; (4) traction force, power demand, and battery range modelling using sensitivity analysis over a 250 km route; and (5) preliminary economic comparison of the pure electric, hybrid, and conventional diesel options across per-km, per-cycle, per-tonne, and per-tonne-km cost metrics. Key findings are as follows. The pure electric CR130EVT with 783 kWh battery capacity can complete a one-way 250 km trip within normal consumption bounds of 2.0–2.7 kWh/km with a 90% usable State of Charge (SOC) window (704.7 kWh usable), leaving a positive SOC margin at the destination terminal. Under adverse operating conditions (energy consumption ≥ 3.0 kWh/km, e.g. severe cold, strong headwinds, high sustained gradients), the practical range falls to approximately 234.9 km, necessitating a mid-route battery swap or charging support station at approximately km 110–140. A proposed three-station infrastructure layout (S0: Tavan Tolgoi terminal; S1: km 110–140 optional mid-route; S2: Gashuun Sukhait terminal) is presented. The recommended charging infrastructure configuration is Grid + Solar PV + Battery Energy Storage System (BESS), providing peak demand shaving and operational resilience, with an installed capacity requirement of 3–4 MW per terminal station. Economic analysis at baseline parameters (electricity tariff: 300 MNT/kWh; diesel price: 4,250 MNT/L; EV energy consumption: 2.5 kWh/km; diesel fuel consumption: 1.3 L/km) yields total direct operating costs of 1,850 MNT/km for the pure electric variant, 5,175 MNT/km for the hybrid, and 7,025 MNT/km for conventional diesel — making the pure electric vehicle 3.8× cheaper to operate per kilometre than diesel. On a per-tonne-km basis, the pure electric achieves 28.5 MNT/t·km versus 79.6 MNT/t·km (hybrid) and 108.1 MNT/t·km (diesel). With one vehicle completing two 500 km round-trip cycles per day for 330 operational days per year, the annual operating cost saving versus diesel is approximately 1.71 billion MNT per vehicle. For a fleet of 10 vehicles, fleet-level annual savings versus diesel reach approximately 17.08 billion MNT. Payback period on additional EV infrastructure investment of 12 billion MNT (10-vehicle fleet) is estimated at approximately 1.09 years — a highly compelling economic case for electrification transition. The hybrid CR130EVT is identified as a viable transitional solution during the infrastructure build-out phase, when terminal swap stations and mid-route support infrastructure are not yet fully commissioned. The hybrid's diesel engine provides operational flexibility without range anxiety, but its higher per-km cost (5,175 MNT/km vs. 1,850 MNT/km) and retained emissions make it unsuitable as a long-term primary fleet strategy. Lateral stability analysis using a static roll model demonstrates that the CR130EVT combination maintains an adequate theoretical stability margin (critical roll angle θ_cr ≈ 34.3° at B = 3.0 m, h_cg = 2.2 m) but requires strict operational protocols: turning speed not exceeding 20–30 km/h on curves with radius ≤ 25 m; maximum working side slope limited to 6–8°; symmetric coal loading of 60 t per trailer body; and level unloading areas. This thesis concludes that the pure electric CR130EVT, deployed with purpose-designed terminal swap stations and mid-route support, represents the most economically and environmentally advantageous long-term solution for the TT–GS coal transport corridor. Recommendations for next steps include a 1–2 vehicle pilot programme to validate field consumption rates across all four Mongolian seasons, followed by staged fleet electrification.
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    The Study of Remaining Operational Life of Power Transformers
    (German-Mongolian Institute for Resources and Technology, 2026) Otgontsoodol, Tegshbayar; Vandandorj, Ankhbayar, Mr.; Purvee, Ariunbolor, Ph.D.
    Power transformers are critical and expensive components of electrical power networks. Their paper-oil insulation system degrades over time due to heat, moisture, and oxygen. Once the insulation fails, the transformer cannot be repaired on site, making accurate remaining life estimation essential for utility engineers deciding when to schedule maintenance or replacement. This bachelor thesis studies and applies the main engineering methods used to estimate the remaining useful life (RUL) of oil-immersed power transformers. Four calculation methods are studied and applied: (1) the IEEE C57.91 and IEC 60076-7 thermal models, which calculate the hotspot temperature and the rate at which insulation life is consumed under a given load [7,8,16]; (2) the Arrhenius-based degree of polymerisation (DP) kinetic model, which predicts how quickly the cellulose paper insulation loses mechanical strength [17,18]; (3) chemical diagnostic methods including dissolved gas analysis (DGA) [6,12,23,24,25], furan compound analysis [30], and oil quality testing [9,32], which provide indirect evidence of insulation condition without opening the transformer; (4) frequency domain spectroscopy (FDS) [11,15], which estimates the moisture content of the paper insulation. All four methods are combined in a weighted health index (HI) formula that gives a single score for the overall transformer condition [3,10,19,20,21]. Full worked numerical examples are presented for each calculation step, and results are compared against published data from real 500 kV and 750 kV transformers [1]. The study confirms that neglecting moisture content leads to overestimates of remaining life by 20-40 % [3,4,22], highlighting the importance of including moisture measurement in any complete transformer condition assessment [3,4,11].