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Title:Experimental study of reversible AC/HP system for electric vehicles
Author(s):Feng, Lili
Department / Program:Mechanical Sci & Engineering
Discipline:Mechanical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):automotive heat pump
reversible system
electric vehicles
Abstract:Conventional passenger cars use waste heat from internal combustion engine for cabin heating. While for electric vehicles (EV), the energy conversion efficiency is much higher, so that there isn't much waste heat available for cabin heating. A general way to provide heat for EV is to use a positive temperature coefficient (PTC) heater to convert electricity stored in the battery directly into heat by Joule effect. Although electric heaters usually have almost 100% first law efficiency, their second law efficiency is typically very low. For a common electric car, turning on the PTC heater can drain the battery and decrease the drive range dramatically. A heat pump is an alternative way to provide equivalent amount of heat for the cabin with less electric energy consumption due to its higher second law efficiency, and will reduce the drive range reduction of EVs caused by cabin heating. Vapor compression cycle is commonly used for automotive air conditioning. By moderate modification of the air conditioning system, heat pump function can be obtained. A heat pump test setup has been built in the lab based on the heat pump system from a commercially available EV, with necessary measurement instrumentation added. Heating capacity (Q) and heating performance factor (HPF) are the most important performance parameters of the heat pump system. The system characteristics and steady state performance have been studied according to different system parameters including expansion valve opening size, refrigerant charge amount, compressor speed, indoor air mass flow rate, outdoor air face velocity, and ambient and indoor temperatures. The transient behavior can be simulated by using steady state test results for different indoor temperature at each ambient condition. Subcooling control for maximizing HPF and charge imbalance and migration are investigated. Challenges with the current system and opportunities for further study are discussed.
Issue Date:2015-04-29
Rights Information:Copyright 2015 Lili Feng
Date Available in IDEALS:2015-07-22
Date Deposited:May 2015

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