Hydronics

Abstract: The Maisotsenko Cycle (M-Cycle) is a thermodynamic conception which captures energy from the air by utilizing the psychrometric renewable energy available from the latent heat of water evaporating into the air. The cycle is well-known in the air-conditioning (AC) field due to its potential of dew-point evaporative cooling. However, its applicability has been recently expanded in several energy recovery applications. Therefore, the present study provides the overview of M-Cycle and its application in various heating, ventilation, and air-conditioning (HVAC) systems; cooling systems; and gas turbine power cycles. Principle and features of the M-Cycle are discussed in comparison with conventional evaporative cooling, and consequently the thermodynamic limitation of the cycle is highlighted. It is reported that the standalone M-Cycle AC (MAC) system can achieve the AC load efficiently when the ambient air humidity is not so high regardless of ambient air temperature. Various modifications in MAC system design have been reviewed in order to investigate the M-Cycle applicability in humid regions. It is found that the hybrid, ejector, and desiccant based MAC systems enable a huge energy saving potential to achieve the sensible and latent load of AC in humid regions. Similarly, the overall system performance is significantly improved when the M-Cycle is utilized in cooling towers and evaporative condensers. Furthermore, the M-Cycle conception in gas turbine cycles has been realized recently in which the M-Cycle recuperator provides not only hot and humidified air for combustion but also recovers the heat from the turbine exhaust gases. The M-Cycle nature helps to provide the cooled air for turbine inlet air cooling and to control the pollution by reducing NOx formation during combustion. The study reviews three distinguished Maisotsenko gas turbine power cycles and their comparison with the conventional cycles, which shows the M-Cycle significance in power industry.

Abstract: A method and an apparatus for cooling, preferably within an enclosure, a diversity of heat-generating components, with at least some of the components having high-power densities and others having low-power densities. Heat generated by the essentially relatively few high-power-density components, such as microprocessor chips for example, is removed by direct liquid cooling, whereas heat generated by the more numerous low-power or low-watt-density components, such as memory chips for example, is removed by liquid-assisted air cooling in the form of a closed loop comprising a plurality of heating and cooling zones that alternate along the air path.

Abstract: A cooling system for providing conditioned air to a facility includes a chiller or other cooling subsystem, a cooling tower subsystem and one or more air handling units or process cooling units. The cooling subsystem may advantageously include one or more chillers (e.g., variable speed chillers, constant speed chillers, absorption chillers, etc.) and chilled fluid pumps. The cooling tower subsystem includes one or more cooling tower units and condenser fluid pumps. In some implementations, the air handling unit has a cooling coil and a variable volume fan. In some implementations, direct expansion (DX) cooling systems comprise compressors, evaporators and air-cooled, water-cooled or evaporatively-cooled condensing systems. Such systems can be controlled to reduce energy waste, improve occupant comfort and/or improve the thermal characteristics of the process cooling unit. The cooling system further comprises a control system which is configured to evaluate a cooling load value at the air handling unit and use the cooling load value to calculate at least one operational setpoint. The operational setpoint may advantageously be selected to improve the energy efficiency of the overall cooling system.