A transport refrigeration system comprising: a prime mover having a coolant circuit; and a transport refrigeration unit including a first compressor stage, a second compressor stage, a heat rejection heat exchanger, an expansion device and a heat absorption heat exchanger connected to form a closed loop refrigeration circuit, wherein the heat rejection heat exchanger comprises: a first tube bank including at least a first and a second flattened tube segments extending longitudinally in a spaced, parallel relationship; a second tube bank including at least a first group of flattened tube segments and a second group of flattened tube segments extending longitudinally in a spaced, parallel relationship, the second tube bank disposed behind the first tube bank with a leading edge of the second tube bank spaced from a trailing edge of the first tube bank, the first group of flattened tube segments is fluidly coupled to the first tube bank and is configured to receive a refrigerant (R C) from the second compressor stage, and the second group of flattened tube segments is configured to receive a coolant, the second group of flattened tube segments being arranged in fluid communication with the coolant circuit; wherein the first tube bank or the second tube bank further comprises another group of flattened tube segments, the another group of flattened tube segments being configured to receive intercooler refrigerant (R I) from the first compressor stage before being supplied to the second compressor stage; and a fan configured to provide an airflow across the first tube bank and the second tube bank sequentially. a prime mover having a coolant circuit; and a transport refrigeration unit including a first compressor stage, a second compressor stage, a heat rejection heat exchanger, an expansion device and a heat absorption heat exchanger connected to form a closed loop refrigeration circuit, wherein the heat rejection heat exchanger comprises: a first tube bank including at least a first and a second flattened tube segments extending longitudinally in a spaced, parallel relationship; a second tube bank including at least a first group of flattened tube segments and a second group of flattened tube segments extending longitudinally in a spaced, parallel relationship, the second tube bank disposed behind the first tube bank with a leading edge of the second tube bank spaced from a trailing edge of the first tube bank, the first group of flattened tube segments is fluidly coupled to the first tube bank and is configured to receive a refrigerant (R C) from the second compressor stage, and the second group of flattened tube segments is configured to receive a coolant, the second group of flattened tube segments being arranged in fluid communication with the coolant circuit; a first tube bank including at least a first and a second flattened tube segments extending longitudinally in a spaced, parallel relationship; a second tube bank including at least a first group of flattened tube segments and a second group of flattened tube segments extending longitudinally in a spaced, parallel relationship, the second tube bank disposed behind the first tube bank with a leading edge of the second tube bank spaced from a trailing edge of the first tube bank, the first group of flattened tube segments is fluidly coupled to the first tube bank and is configured to receive a refrigerant (R C) from the second compressor stage, and the second group of flattened tube segments is configured to receive a coolant, the second group of flattened tube segments being arranged in fluid communication with the coolant circuit; wherein the first tube bank or the second tube bank further comprises another group of flattened tube segments, the another group of flattened tube segments being configured to receive intercooler refrigerant (R I) from the first compressor stage before being supplied to the second compressor stage; and a fan configured to provide an airflow across the first tube bank and the second tube bank sequentially.