A heat engine system , comprising: a working fluid circuit having a high pressure side and a low pressure side and configured to flow a working fluid therethrough, wherein at least a portion of the working fluid circuit contains the working fluid in a supercritical state, and the working fluid comprises carbon dioxide; a plurality of heat exchangers (120a-120d), wherein each of the heat exchangers is fluidly coupled to and in thermal communication with the high pressure side of the working fluid circuit, configured to be fluidly coupled to and in thermal communication with a heat source, and configured to transfer thermal energy from the heat source to the working fluid within the high pressure side; a plurality of recuperators (130a-130c), wherein each of the recuperators is fluidly coupled to the working fluid circuit and configured to transfer thermal energy between the high pressure side and the low pressure side of the working fluid circuit, wherein the plurality of heat exchangers and the plurality of recuperators are sequentially and alternatingly disposed in the working fluid circuit; an expander fluidly coupled to the working fluid circuit, disposed between the high pressure side and the low pressure side, and configured to convert a pressure drop in the working fluid to mechanical energy; a driveshaft coupled to the expander and configured to drive a device with the mechanical energy; a system pump fluidly coupled to the working fluid circuit between the low pressure side and the high pressure side of the working fluid circuit and configured to circulate or pressurize the working fluid within the working fluid circuit; and a cooler in thermal communication with the working fluid in the low pressure side of the working fluid circuit and configured to remove thermal energy from the working fluid in the low pressure side of the working fluid circuit. a working fluid circuit having a high pressure side and a low pressure side and configured to flow a working fluid therethrough, wherein at least a portion of the working fluid circuit contains the working fluid in a supercritical state, and the working fluid comprises carbon dioxide; a plurality of heat exchangers (120a-120d), wherein each of the heat exchangers is fluidly coupled to and in thermal communication with the high pressure side of the working fluid circuit, configured to be fluidly coupled to and in thermal communication with a heat source, and configured to transfer thermal energy from the heat source to the working fluid within the high pressure side; a plurality of recuperators (130a-130c), wherein each of the recuperators is fluidly coupled to the working fluid circuit and configured to transfer thermal energy between the high pressure side and the low pressure side of the working fluid circuit, wherein the plurality of heat exchangers and the plurality of recuperators are sequentially and alternatingly disposed in the working fluid circuit; an expander fluidly coupled to the working fluid circuit, disposed between the high pressure side and the low pressure side, and configured to convert a pressure drop in the working fluid to mechanical energy; a driveshaft coupled to the expander and configured to drive a device with the mechanical energy; a system pump fluidly coupled to the working fluid circuit between the low pressure side and the high pressure side of the working fluid circuit and configured to circulate or pressurize the working fluid within the working fluid circuit; and a cooler in thermal communication with the working fluid in the low pressure side of the working fluid circuit and configured to remove thermal energy from the working fluid in the low pressure side of the working fluid circuit. <EOS>