A refrigeration unit includes a compressor, a first heat exchanger, a second heat exchanger, a water pump, and a heat exchanging arrangement. The heat exchanging arrangement includes a main casing having a receiving cavity divided into a water atomizing compartment and one water showering compartment, a water atomizing unit, a water showering head, a fill material unit provided underneath the water showering head, and a water collection basin provided underneath the water atomizing unit and the fill material unit. A predetermined amount of heated water from the first heat exchanger is guided to flow to the water showering head and the water in the water showering head is sprinkled on the fill material unit. A predetermined amount of water from the water pump guided to flow to the water atomizing unit and the water flowing to the water atomizing unit is sprayed and atomized in the water atomizing compartment.