From Cool Thermodynamics: The Engineering and Physics of Predictive, Diagnostic and Optimization Methods for Cooling Systems


C1. Absorption Basics and Absorption Versus Mechanical Chillers

Absorption cycles are similar to mechanical-chiller cycles in utilizing a condenser, evaporator and expansion device (see the schematic in Figure 2.18). The difference lies in how the low-pressure vapor that exits the evaporator is converted into the high-pressure vapor that enters the condenser. Instead of the work-driven compressor of a mechanical chiller, thermal power is the driving force. The heat is usually delivered in the form of hot water or steam, and is commonly derived from the combustion of natural gas, industrial waste heat, geothermal sources, or solar energy collection.

Figure 2.18: Schematic of an absorption chiller cycle. This particular illustration is for a single-stage steam-fired unit with a non-volatile solute as in the LiBr-water pair. The same schematic applies equally well to a hot water-fired device. Also, the heat pump mode involves extracting the useful effect as heating at the condenser/absorber, as opposed to the cooling mode where the useful effect is heat removal at the evaporator.

A vapor-compression chiller produces its cooling at an evaporator (a heat pump produces its heating at a condenser). The corresponding absorption system includes two additional heat reservoirs: a generator and an absorber. A volatile working fluid (refrigerant) is partially separated from the carrier solution by the heat input at the generator. The refrigerant and solution are subsequently recombined in an exothermic process at the absorber. The absorber functions as a heat rejection unit (in addition to the condenser). Were the absorber...

Products & Services
HVAC Chillers
Heating, ventilation and air conditioning (HVAC) chillers are refrigeration systems that provide cooling for industrial and commercial applications. They use water, oils or other fluids as refrigerants.
Combined Heat and Power (CHP) Modules
Cogeneration equipment produces power and thermal energy from a common fuel source, generally one that is considered to be a waste product from another process.
Chillers (industrial)
Industrial chillers cool water using refrigeration cycles to provide a constant stream of coolant for manufacturing and laboratory processes.
Condensers are devices which accept a vapor stream and convert it to a liquid using heat transfer and/or compression.They are used in steam turbines for power plants, in cooling units for in-process fluids, and in air conditioning systems for buildings and automobiles.
Refrigerants, Antifreezes, and Cooling Liquids
Primary refrigerants use a thermodynamic or adiabatic process (evaporation-condensation cycles) to remove heat and cool a region. Secondary refrigerants such as antifreeze liquids provide cooling solely through heat transfer.

Topics of Interest

D. THERMOACOUSTIC CHILLER In thermoacoustic refrigeration, high-intensity sound waves are used instead of compressors to set up a standing wave in a closed resonator tube filled with inert gases, and...

"Have no fear of perfection - you'll never reach it. " -Salvador Dali A. OBJECTIVES AND MOTIVATION Let's adopt the perspective of the designer or manufacturer of absorption systems. The operating...

Sealing techniques figure heavily into what technology makes sense in different portions of the refrigeration cycle. Supermarket refrigeration systems, rooftop chillers, walk-in fast-food-restaurant...

CHAPTER LIST Chapter 41: Absorption Cooling, Heating, and Refrigeration Equipment Chapter 42: Forced-Circulation Air Coolers Chapter 43: Component Balancing in Refrigeration Systems Chapter 44:...

HEAT GENERATORS (HEATING PLANTS) Considerable improvements in the seasonal efficiency of conventional heating plant equipment, such as boilers and furnaces, were made over the last several decades.