Generate Cold From Waste Heat
From small plants to industrial large scale plants – your project is in good hands. In the area of refrigeration plant construction, the dominating fields of activity over the past years were: split units, screwtype water chillers, turbo water chillers and absorption chillers in complex interconnections with diverse heat generators.AGO AG Energie + Anlagen can exclusively provide a highly interesting product for the absorption process of refrigeration for temperatures below 0°C due to the collaboration with the ILK Dresden.
- Less energy consumption unlike traditional separate production
- Reduction of CO2 emissions
- Reduction of pollutant emissions
- Possible use of waste heat flows for the generation of thermal energy for miscellaneous refrigeration requirements
- Substitution of premium electric energy by “inferior” thermal energy in form of waste heat
- Reduction of the life cycle costs due to lower operational costs
- Lower consumption of premium electrical energy
- Lower electrical power input
- Lower maintenance and repair costs
- Long life cycle due to fewer moving components
- Reliability, superior availability
- Food and beverage industry
- Milk cooling
- Large bakeries
- Deep freeze and cold storage
- Fish processing facilities
- Fruit and vegetable cooling
- Chemical and petrochemical industry
- Chips and deep-frying factories
- Air cooling of gas turbines
- Powered by waste heat at low temperature from 90°C
- Utilization of “free” waste heat
- Possibility of trigeneration in connection with combined heat and power plants (CHPs)
- Fully automatic operation mode
- Favorable partial load performance at a proportional consumption of the required heat input
- Easy handling
- Generation of effective temperatures of down to -30°C
- Adjustment of COP to individual requirements
- Fault-free operation due to simple design
- Low power consumption, 85 % of primary energy savings
- Not subject to the regulation on fluorinated greenhouse gases
- Low sound power level and structure-borne sound propagation (low noise level, no vibrations)
- Use of natural refrigerants (ODP and GWP =0)
- Oil-free refrigerant
- Refrigeration temperatures of down to below 0°C are possible
- Modular structure
- Compact design by using plate heat exchangers
- Less refrigerant required
- Easy installation
- Individual design allows for integration into existing systems (tri-generation)
- Outdoor installation is possible
The profitability of the ammonia-water absorption chiller can only be calculated by taking into consideration the following criteria. An individual analysis of the overall system is always necessary.
Costs for refrigeration plants depend on design parameters, such as:
- Refrigerating capacity
- Heating medium temperature (depends on the temperature of the refrigerant)
- Temperature of the refrigerant
- Re-cooling temperature or cooling water temperature
- Rectification efforts, etc.
The profitability of a NH3 absorption chiller can only be calculated taking into consideration:
- the exact conditions of the location
- the current operating costs (such as gas price, water costs, sewage costs and electricity costs)
- the heat price, electricity credits in case of CHP waste heat (cogeneration bonus)
- the costs of saved electricity and operating costs
- the costs saved due to the lower electrical connection power
- the determination of the reference plant
- the necessity of redundancy, etc.
Usable heat sources
- Industrial waste heat in form of water, steam and thermal oil
- CHP waste heat
- Waste heat from thermal post-combustion
- Solar heat
- Biomass plants and biogas plants
Heat energy in preference to electric energy
For the refrigeration generation, electrically driven compression-type chillers are applied by default. In times of high energy costs, a cost-saving alternative can be offered:
- The absorption chiller powered by waste heat.
- It works according to a principle, which is already known since the early 19th century.
- Since nowadays, the conscious and economical use of energy is also a decisive selection criterion in the area of refrigeration engineering, the absorption chiller powered by waste heat is gaining more and more importance.
According to the basic laws of thermodynamics, heat moves spontaneously only from a higher to a lower temperature level. Refrigeration systems, however, transport heat from a lower temperature level (cooling application) to a higher one. This process requires the use of energy.
In the absorption chiller, the refrigerant (ammonia) absorbs the heat flow Q0 on the “cold side” at a temperature t0 and evaporates during the process. The refrigerant vapour is absorbed by a liquid solution (aqueous ammonia solution), which has a higher dissolving power than the refrigerant. The heat flow QAbs released during this process needs to be dissipated.
A pump transports the incompressible solution with the refrigerant to the higher pressure level using low energy input.
The refrigerant escapes from the solution by heat supply QH to the boiler (actuator of the process) and is liquefied in the condenser while dissipating heat QC.
The refrigerant and solution cycles are closed by means of relief valves (expansion valve and solution valve). In order to increase energetic efficiency, a solution heat exchanger is installed in the solution cycle.
The refrigerant ammonia has excellent thermodynamic characteristics. Therefore, it is one of the classic refrigerants, which has already been used by Linde in his refrigeration systems and was thus made available for a wide variety of applications. To this day, it has not lost its significance. Despite its toxicity and flammability (within tightly defined limits), the chillers with ammonia as refrigerant are safe according to state-of-the-art technology.