Serial type pump comprising a heat exchanger

A pump unit comprising:

• a primary piston pump,
• a secondary piston pump,
• a flow path fluidically connecting in series the primary piston pump and the secondary piston pump, wherein:
• the pump unit is configured for executing a duty cycle comprising a delivery-and-fill phase, in which the primary piston pump supplies a flow of liquid to the secondary piston pump, and during the delivery-and-fill phase, the flow of liquid supplied by the primary piston pump is partly used for filling up the secondary piston pump and partly used for maintaining continuous flow of liquid dispensed at an outlet of the secondary piston pump,
• the flow path comprises a heat exchanger, wherein liquid supplied by the primary piston pump passes through the heat exchanger before being supplied to the secondary piston pump, and
• the heat exchanger is configured for reducing a temperature difference between a temperature of liquid supplied to the heat exchanger and a temperature of the secondary piston pump influenced by flow rates of liquid supplied by the primary piston pump, and enforced by the heat exchanger, during the delivery-and-fill phase, in that the heat exchanger is kept at a temperature of the secondary piston pump, so that after having passed the heat exchanger, liquid supplied to the secondary piston pump during the delivery-and-fill phase has substantially the same temperature as the temperature of the secondary piston pump,
• and further comprising one or more of the following:
• a thermostatic heating element configured to keep both the heat exchanger and the secondary piston pump at a predefined temperature;
• the heat exchanger comprises a heat reservoir and one or more capillaries in thermal contact with the heat reservoir;
• a control unit configured to superpose at least one corrective movement to at least one of the primary piston pump and secondary piston pump so as to compensate for volumetric effects that are due to temperature variations of the liquid;
• a common heat reservoir thermally coupling the heat exchanger and the secondary piston pump;
• the pump unit being configured to execute the duty cycle such that the delivery-and-fill phase extends over less than 10% of the duty cycle;
• or
• the heat exchanger comprising a pattern of heat exchange elements configured to intensify the thermal contact of liquid to the heat exchanger.