System and method for controlling coolant of vehicle

A method of controlling coolant of a vehicle, comprising:

• as a first outside air temperature comparison step, comparing an outside-air temperature of an outside air with a reference temperature to determine where to circulate coolant discharged from an engine between an automatic transmission fluid (ATF) warmer and a heater, and to determine when to stop heat exchange between the coolant and an exhaust heat recovery system;
• as a circulation step, based on the outside-air temperature of the outside air, supplying the coolant discharged from the exhaust heat recovery system to either the ATF warmer or the heater;
• as an exhaust heat recovery step, supplying the coolant discharged from the engine to the exhaust heat recovery system;
• as a water temperature comparison step, determining whether an exhaust-heat-recovery-system coolant temperature of the coolant discharged from the exhaust heat recovery system exceeds a bypass temperature to allow the coolant to bypass the exhaust heat recovery system;
• and
• as a bypass step, based on the exhaust-heat-recovery-system coolant temperature of the coolant discharged from the exhaust heat recovery system exceeding the bypass temperature, allowing exhaust gas to flow through the exhaust heat recovery system such that the exhaust gas has reduced or no heat exchange with the coolant.

A method of controlling coolant of a vehicle, comprising:

• as a second outside air temperature comparison step, comparing an outside-air temperature of an outside air with a reference temperature to determine an operating mode of an exhaust heat recovery system and an integrated flow control valve;
• as a mode entry step, based on the outside-air temperature of the outside air, causing the integrated flow control valve to enter a first operating mode;
• as a bypass determination step, determining whether exhaust gas passes through the exhaust heat recovery system with reduced or no exchanging heat with the coolant;
• as a flow stop determination step, determining whether the integrated flow control valve is controlled in a flow stop state;
• as a flow stop releasing step, releasing a flow stop control of the integrated flow control valve;
• as a water temperature condition comparison step, determining whether an exhaust-heat-recovery-system coolant temperature of the coolant discharged from the exhaust heat recovery system is below a recovery entry temperature, which is preset to trigger entry into exhaust heat recovery control in the exhaust heat recovery system, while the exhaust-heat-recovery-system coolant temperature of the coolant discharged from the exhaust heat recovery system exceeds an engine coolant temperature of the coolant discharged from an engine;
• and
• as an exhaust heat recovery entry step, controlling the exhaust heat recovery system to recover exhaust heat.