The present disclosure relates generally to the field of heat pump systems using a vapor compression cycle, and more specifically to use of such systems in heating, ventilation, air conditioning, refrigeration, fluid heating and chilling.
Various systems are available for heating, ventilation, air conditioning, refrigeration, fluid heating and chilling. Such systems can be dedicated to heating or to cooling, or, for example, in the case of heat pump systems, the direction of a refrigerant flow can be reversed through heat exchangers in forced-air systems to either allow for absorption of heat from a space for the cooling such space or for absorption heat from the outdoors for the heating of such space. In this type of arrangement, forced-air flows over the heat exchanger through ductwork to such space.
Heat pump systems may also be used in ductless systems, including direct expansion systems, where a refrigerant heat exchanger is typically in the space to be heated and/or cooled. Variable refrigerant flow systems are examples of direct expansion systems and may offer benefits in certain applications, including improved energy efficiency. Such systems may use one or more condensing units and provide refrigerant to one or more evaporator units in a ductless manner.
In certain situations, conventional direct expansion systems may involve safety issues in that because one or more of the heat exchangers is in the space being heated and/or cooled, in the event of a refrigerant leak, the refrigerant may leak into such space. Certain refrigerant gas is heavier than air and can displace oxygen in a room or space, and in extreme situations, could displace a sufficient amount of oxygen from a space such that a person could succumb to suffocation. As certain refrigerants cannot generally be detected by a person through sight, smell, or otherwise, the severity of such a refrigerant leak could become grave.
Therefore, there is a need for heating and chilling systems for a fluid, such as water, which provide increased efficiency and which also lessen the risk of injury to persons in the event of a refrigerant leak.