ShareGL2012 highlights: technologies needed in order to raise uptake of natural refrigerants
Prof. Pega Hrnjak presented technologies that could advance the position of major natural refrigerants at the 2012 Gustav Lorentzen Conference on Natural Refrigerants. He claims that hydrocarbons, ammonia and CO2 could become strong contenders for dominant positions in certain applications in the world if the right technologies were used.
Prof. Pega Hrnjak presented technologies that could advance the position of major natural refrigerants at the 10th Gustav Lorentzen Conference on Natural Refrigerants in Delft, the Netherlands, in June 2012. He claims that hydrocarbons (HCs) , ammonia and CO2 could become strong contenders for dominant positions in certain applications in the world if the right technologies were used.
For instance, development low charged systems, chillers especially, that could be placed outdoors on rooftops and used with a secondary coolant, would be beneficial to the uptake of ammonia, which needs to be separated from the public and food, especially in closed spaces. There is excellent potential for market penetration of small low-charge ammonia systems, for refrigeration or air conditioning. The full utilisation of aluminium for ammonia is another unrealized source of greater competiveness.
Charge minimization could also increase opportunities to expand the use of HCs and recent results show that such systems could operate with less than 50 g per kW of cooling capacity. The main issues for CO2 systems are to reduce costs and improve performance. Therefore, work recovery options such as ejectors, expanders and the like may bring the most benefit. Improving the efficiency of the compression process, e.g. by reducing the irreversibility relating to high discharge temperatures, could also be beneficial.
Ammonia and CO2 show the best potential for low-charge systems, but for different reasons. Because of ammonia’s very high latent heat, it requires lower mass flow for the same capacity than any other fluid. CO2 has a low pressure drop due to dense vapour and low sensitivity to pressure drop; therefore low-charge systems a good option, especially with microchannel heat exchangers.
Technologies needed to advance the position of major natural refrigerants HC, NH3 and CO2, P. Hrnjak,
This paper can be downloaded wia the IIR’s Fridoc database (free for IIR members within the framework of their quota of free downloads). You just have to login and search for the paper via the Fridoc database.
For instance, development low charged systems, chillers especially, that could be placed outdoors on rooftops and used with a secondary coolant, would be beneficial to the uptake of ammonia, which needs to be separated from the public and food, especially in closed spaces. There is excellent potential for market penetration of small low-charge ammonia systems, for refrigeration or air conditioning. The full utilisation of aluminium for ammonia is another unrealized source of greater competiveness.
Charge minimization could also increase opportunities to expand the use of HCs and recent results show that such systems could operate with less than 50 g per kW of cooling capacity. The main issues for CO2 systems are to reduce costs and improve performance. Therefore, work recovery options such as ejectors, expanders and the like may bring the most benefit. Improving the efficiency of the compression process, e.g. by reducing the irreversibility relating to high discharge temperatures, could also be beneficial.
Ammonia and CO2 show the best potential for low-charge systems, but for different reasons. Because of ammonia’s very high latent heat, it requires lower mass flow for the same capacity than any other fluid. CO2 has a low pressure drop due to dense vapour and low sensitivity to pressure drop; therefore low-charge systems a good option, especially with microchannel heat exchangers.
Technologies needed to advance the position of major natural refrigerants HC, NH3 and CO2, P. Hrnjak,
This paper can be downloaded wia the IIR’s Fridoc database (free for IIR members within the framework of their quota of free downloads). You just have to login and search for the paper via the Fridoc database.