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Does
Your Company Need to Significantly
Cooler, Cleaner, Greener Power & Energy Solutions™ project development services are one of our many specialties. These projects are Kyoto Protocol compliant and generate clean energy and significantly fewer greenhouse gas emissions. Unlike most companies, we are equipment supplier/vendor neutral. This means we help our clients select the best equipment for their specific application. This approach provides our customers with superior performance, decreased operating expenses and increased return on investment. Cogeneration
Technologies, located in Houston, Texas, provides
project development services that generate clean energy and
significantly reduce greenhouse
gas emissions and carbon
dioxide emissions. Included in this are our
turnkey "ecogeneration™"
products and services which includes renewable
energy technologies, waste to
energy, waste to watts™ and waste
heat recovery solutions. Other project development
technologies include; Anaerobic
Digester, Anaerobic Lagoon, Biogas
Recovery, BioMethane, Biomass
Gasification, and Landfill Gas
To Energy, project development services.
For more information: call us at: 832-758-0027 We are Renewable Energy Technologies specialists and develop clean power and energy projects that will generate a "Renewable Energy Credit," Carbon Dioxide Credits and Emission Reduction Credits. Some of our products and services solutions and technologies include; Absorption Chillers, Adsorption Chillers, Automated Demand Response, Biodiesel Refineries, Biofuel Refineries, Biomass Gasification, BioMethane, Canola Biodiesel, Coconut Biodiesel, Cogeneration, Concentrating Solar Power, Demand Response Programs, Demand Side Management, Energy Conservation Measures, Energy Master Planning, Engine Driven Chillers, Geothermal Heatpumps, Groundsource Heatpumps, Solar CHP, Solar Cogeneration, Rapeseed Biodiesel, Solar Electric Heat Pumps, Solar Electric Power Systems, Solar Heating and Cooling, Solar Trigeneration, Soy Biodiesel, Trigeneration, and Watersource Heatpumps. How Does an Absorption
Chiller Work?
Absorption
chillers use heat instead of mechanical energy to provide cooling. A
thermal compressor consists of an absorber, a generator, a pump, and a
throttling device, and replaces the mechanical vapor compressor. In
the chiller, refrigerant vapor from the evaporator is absorbed by a
solution mixture in the absorber. This solution is then pumped to the
generator. There the refrigerant re-vaporizes using a waste steam heat
source. The refrigerant-depleted solution then returns to the absorber via
a throttling device. The two most common refrigerant/ absorbent mixtures
used in absorption chillers are water/lithium bromide and ammonia/water. Compared
with mechanical chillers, absorption chillers have a low coefficient of
performance (COP = chiller load/heat input). However, absorption chillers
can substantially reduce operating costs because they are powered by
low-grade waste heat. Vapor compression chillers, by contrast, must be
motor- or engine-driven. Low-pressure,
steam-driven absorption chillers are available in capacities ranging from
100 to 1,500 tons. Absorption chillers come in two commercially available
designs: single-effect and double-effect. Single-effect machines provide a
thermal COP of 0.7 and require about 18 pounds of
15-pound-per-square-inch-gauge (psig) steam per ton-hour of cooling.
Double-effect machines are about 40% more efficient, but require a higher
grade of thermal input, using about 10 pounds of 100- to 150-psig steam
per ton-hour. A
single-effect absorption machine means all condensing heat cools and
condenses in the condenser. From there it is released to the cooling
water. A double-effect machine adopts a higher heat efficiency of
condensation and divides the generator into a high-temperature and a
low-temperature generator.
In
short, absorption cooling may fit when a source of free or low-cost heat
is available, or if objections exist to using conventional refrigeration.
Essentially, the low-cost heat source displaces higher-cost electricity in
a conventional chiller. In
Practice
Annual
Savings = 300 tons x (12,000 Btu/ton / 4.0) x 4,000 hrs/yr x $0.05/kWh x
kWh/3,413 Btu = $52,740
Determine
the cost-effectiveness of displacing a portion of your cooling load with a
waste steam absorption chiller by taking the following steps:
Absorption Chiller Refrigeration CycleThe basic cooling cycle is the same for the absorption and electric chillers. Both systems use a low-temperature liquid refrigerant that absorbs heat from the water to be cooled and converts to a vapor phase (in the evaporator section). The refrigerant vapors are then compressed to a higher pressure (by a compressor or a generator), converted back into a liquid by rejecting heat to the external surroundings (in the condenser section), and then expanded to a low- pressure mixture of liquid and vapor (in the expander section) that goes back to the evaporator section and the cycle is repeated. The basic difference between the electric chillers and absorption chillers is that an electric chiller uses an electric motor for operating a compressor used for raising the pressure of refrigerant vapors and an absorption chiller uses heat for compressing refrigerant vapors to a high-pressure. The rejected heat from the power-generation equipment (e.g. turbines, microturbines, and engines) may be used with an absorption chiller to provide the cooling in a CHP system. The basic absorption cycle employs two fluids, the absorbate or refrigerant, and the absorbent. The most commonly fluids are water as the refrigerant and lithium bromide as the absorbent. These fluids are separated and recombined in the absorption cycle. In the absorption cycle the low-pressure refrigerant vapor is absorbed into the absorbent releasing a large amount of heat. The liquid refrigerant/absorbent solution is pumped to a high-operating pressure generator using significantly less electricity than that for compressing the refrigerant for an electric chiller. Heat is added at the high-pressure generator from a gas burner, steam, hot water or hot gases. The added heat causes the refrigerant to desorb from the absorbent and vaporize. The vapors flow to a condenser, where heat is rejected and condense to a high-pressure liquid. The liquid is then throttled though an expansion valve to the lower pressure in the evaporator where it evaporates by absorbing heat and provides useful cooling. The remaining liquid absorbent, in the generator passes through a valve, where its pressure is reduced, and then is recombined with the low-pressure refrigerant vapors returning from the evaporator so the cycle can be repeated. Absorption chillers are used to generate cold water (44°F) that is circulated to air handlers in the distribution system for air conditioning. "Indirect-fired" absorption chillers use steam, hot water or hot gases steam from a boiler, turbine or engine generator, or fuel cell as their primary power input. Theses chillers can be well suited for integration into a CHP system for buildings by utilizing the rejected heat from the electric generation process, thereby providing high operating efficiencies through use of otherwise wasted energy. "Direct-fired" systems contain natural gas burners; rejected heat from these chillers can be used to regenerate desiccant dehumidifiers or provide hot water. Commercially absorption chillers can be single-effect or multiple-effect. The above schematic refers to a single-effect absorption chiller. Multiple-effect absorption chillers are more efficient and discussed below. Multiple-Effect Absorption Chillers In a single-effect absorption chiller, the heat released during the chemical process of absorbing refrigerant vapor into the liquid stream, rich in absorbent, is rejected to the environment. In a multiple-effect absorption chiller, some of this energy is used as the driving force to generate more refrigerant vapor. The more vapor generated per unit of heat or fuel input, the greater the cooling capacity and the higher the overall operating efficiency. A double-effect chiller uses two generators paired with a single condenser, absorber, and evaporator. It requires a higher temperature heat input to operate and therefore they are limited in the type of electrical generation equipment they can be paired with when used in a CHP System. Triple-effect chillers can achieve even higher efficiencies than the double-effect chillers. These chillers require still higher elevated operating temperatures that can limit choices in materials and refrigerant/absorbent pairs. Triple-effect chillers are under development by manufacturers working in cooperation with the U.S. Department of Energy. How Does an Engine Driven Chiller Work? Packaged natural gas engine-driven water chillers and direct expansion (DX) units are now available. Commercially proven custom and packaged engine-driven refrigeration units offer excellent reliability and economic advantages for ice rinks, refrigerated warehouses and other applications. The industry is also focusing on developing small, engine-driven heating and cooling systems suitable for small commercial applications. Operation: Engine-driven cooling systems employ a conventional vapor compression cycle. Their main components are the compressor, condenser, expansion valve and evaporator. * Requires no more room than conventional electric chillers * Lowest operating cost of any available chiller * Depending on electric rates and natural gas rates, an engine driven chiller may operate at up to 1/2 of the cost of direct-fired absorption chillers * Like absorption chillers, engine driven chillers reduce on-peak electric demand charges. * Depending on your electric and/or natural gas supplier, there may be rebates available for purchasing a new absorption chiller or engine driven chiller from your utility supplier. * Environmentally friendly. For more information on absorption chillers, call us at: 832-758-0027 * Some of the above information from the Department
of Energy website with permission. |
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