Title: MODELING OF ADVANCED HEAT PUMP CYCLES AND AERODYNAMIC DESIGN OF A SMALL-SCALE CENTRIFUGAL COMPRESSOR FOR ELECTRIC VEHICLES
Date: March 31st 9am-11am
Location: EGR-4164B
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https://umd.zoom.us/j/2112804847?pwd=Q0lhdHp2NTZuNG40OTBodW10RjdjQT09
Meeting ID: 211 280 4847
Passcode: 65hXXk
Committee members:
Dr. Amir Riaz
Dr. Bao Yang
Dr. Jelena Srebric
Dr. Peter B. Sunderland, Dean’s Representative
Dr. Reinhard Radermacher, Chair
Dr. Yunho Hwang
Abstract:
Unlike conventional vehicles powered by internal combustion engines, electric vehicles do not have enough waste heat to provide sufficient heating to the cabin. Thus, an additional heating system, such as a heat pump, is needed. However, its performance decreases significantly when the ambient temperature is low. The new kangaroo heat pump cycle (KC) is proposed to increase the heating capacity in low temperature climates. It is an enhanced flash tank-based vapor injection heat pump cycle (FT-VIC). A sub-cycle is added to the system to increase the refrigerant inlet quality entering the flash tank, which leads to a higher refrigerant mass flow rate and heating capacity. Because KC has higher heating capacity, the heating needed from the electric heater can be reduced, thus reducing the energy consumption and increasing the driving distance. In this study, thermodynamic models were developed for the basic heat pump cycle, FT-VIC, and KC. And their annual energy consumption and life cycle climate performance (LCCP) were evaluated based on the SAE J2766 standard. Results show that KC did provide more heating capacity, but its energy consumption also increases a lot. In terms of energy saving, KC is only superior in extremely cold climates. At -15°C, KC saves 13.8% energy compared to BC, and saves 2.7% energy compared to FT-VIC. In addition, KC also has higher LCCP than other cycles. Transient models were also developed to assess their performance in urban driving conditions. KC heated up the cabin faster than other cycles but also consumed more energy. In addition, a small-scale centrifugal compressor was designed for an electric vehicle. Results show that despite its smaller size and high efficiency at the design point, it has poor efficiency at the off-design point and a narrow operating range. Future study on methods for improving its operating range is needed.