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ENERGY SAVING Condenser. Photo: Cofely Refrigeration BV >


controllability. This is said to be extremely good, with a minimum of fluctuation and an accuracy of 0.1 °C. Direcht pump systems are exceptionally energy- efficient, but another characteristic – which is also considered a drawback- is the relatively large quan- tity of refrigerant they contain. It is vital that leakages are prevented, both with cost considerations in mind and with regard to the environment


(with R134a).


Should a leak occur, it must be detected and signal- led as quickly as possible. The system is equipped with an automatic freon test for this purpose, which runs a check each night and gives an alarm as soon as the freon percentage is too low (see photo 4). There have in fact been few problems with leakage. To conform to the legal obligations for installations with a refrigerant charge of up to 1000 kg, a mainte- nance contract has been taken out under which the installations are inspected and maintained twice a year including a “sniffer test” using an electronic device capable of detecting even the smallest freon leak. In addition, an extra sniffer test is performed on a further two occasions, bringing the total of tests to four. As qualified F-gas engineers are the only people authorised to work on freon installations, Smits and Derks do not have to spend any time on the installation.


Freon R22 phase out The phase out, and ultimately the ban, of freon R22 is the final stage in the phase out of refrigerants that contain chlorine (CFCs and HCFCs). These refrige- rants are particularly harmful to the ozone layer and are therefore being phased out all over the world. In- ternational agreements have been made, which have been embedded in Dutch and European legislation.


The use of R22 in new plants has been prohibited since 1 January 2004, and since 1 January 2010 the use of virgin R22 to top up existing installations has also been forbidden. However, recycled R22 may be used to top up these installations until 2015. From 1 January 2015, a total ban will apply to topping up existing plants with freon R22. Existing installations will still be permitted to operate, but may no longer be replenished with R22 in any form whatsoever (vir- gin, recycled and/or blended R22 refrigerant). The long-term aim is to phase out the use of any synthetic refrigerants (this includes R134a) by 2030 and to apply instead only natural alternatives such as CO2 and ammonia. The growing interest in these natural refrigerants is already clearly reflecting this trend. Cooling is an essential constituent of mushroom growing. The phase out means that in 2015 it will not be possible to recommission installations containing R22 if for one reason or another (leakage/repair) freon has been lost and needs replacing. To ensure continuity for the future, owners of R22 installations should considered converting the installation to an alternative refrigerant (e.g. R134a), providing this is still financially viable, or otherwise investing in a new cooling installation. When making this decision- and at the design stage with new-builds- it is impor- tant to obtain the best advice, taking into account not just the investment costs but also the operating costs. You are ultimately talking about the total cost of ownership for the lifetime of the system.


Comparison of the main features There are two cooling techniques that are most com- monly applied in climate control; indirect cooling via a chiller with glycol, which is the best-known method, and the lesser-known method of direct coo- ling via a pump system with a directly vaporising refrigerant. They are in fact both pump systems, the difference being that one system is direct while the other is indirect. The table below compares the main features of the two systems:


Alongside a reliable installation that offers accurate control of the temperature after cooling – under all conditions relating to cultivation and external circumstances –energy consumption is crucially important to the mushroom sector. With direct vaporisation of the refrigerant this consumption is


Comparision cooling systems


Direct pump system indirect pump system (chiller)


Refrigerant Heat transfer


Dimensions heat sinks Resistance heat sinks Fan capacity


Pump capacity refrigerant Heat recovery


Inspections/maintenance Subsidy possible


Energy consumption Investment


Automatic freon test.


Henk Derks actively uses the tank temperature and winter operation settings.


Operating costs


freon r134a / ammonia nh3 glycol / water direct


narrower lower lower lower


Free cooling/ winter operation below 8° outside temp. Control. Temp. After cooling Refrigerant charge


possible accurate frequent


larger


higher lower


indirect wider higher higher higher


possible


below 0° outside temp. accurate smaller


eia ( installations with nh3) no lower


less frequent higher higher


lower Source: Henk Tebben Cofely Refrigeration BV


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