Methods and systems for an engine with exhaust gas recirculation

A method executed via instructions stored in non-transitory memory of a controller of an engine system, the controller configured to receive feedback from a thermostat configured to sense a temperature of coolant leaving an engine and direct the coolant to either a supply line fluidly coupled to a heat store or to a bypass, the method, comprising:

• selecting a first mode in response to an engine coolant temperature not being less than a desired threshold coolant temperature range comprising a lower limit and an upper limit, an amount of heat stored in a heat store being greater than or equal to a threshold amount, and a likelihood of condensate formation due to LP-EGR mixing with intake air being less than a threshold likelihood, wherein the first mode further comprises flowing coolant from the engine, through the supply line, and to the heat store by actuating a coolant check valve to and a heat store check valve to third positions;
• selecting a second mode in response to either the engine coolant temperature being within the desired threshold coolant temperature range and the amount of heat stored in the heat store being less than the threshold amount or the engine coolant temperature being less than the desired threshold coolant temperature range and the amount of heat stored in the heat store being greater than or equal to the threshold amount, wherein the amount of heat stored in the heat store is based on the engine coolant temperature and coolant flow through the heat store, and wherein the second mode further comprises flowing coolant from the engine, through the heat store, and to the bypass to increase the amount of heat stored in the heat store, the second mode comprising actuating the coolant check valve and the heat store check valve to first positions;
• selecting a third mode in response to the likelihood of condensate formation being greater than or equal to the threshold likelihood and either the engine coolant temperature being less than the desired threshold coolant temperature range or the amount of heat stored in the heat store being less than the threshold amount, wherein the third mode further comprises flowing coolant from the engine, through the heat store, and to an intake air heat exchanger by actuating the coolant check valve to the first position and the heat store check valve to the second position;
• and
• selecting a fourth mode in response to the engine coolant temperature being within the desired threshold coolant temperature range and the amount of heat stored in the heat store being greater than or equal to the threshold amount, wherein the fourth mode further comprises flowing coolant from the engine to the intake air heat exchanger by actuating the coolant check valve to the second position and the heat store check valve to the third position.