considerably lower (+/- 20-25 %) than with an indi- rect substance. This can be partly attributed to the smaller components needed to achieve the desired result. As a refrigerant of the direct vaporisation type has a greater absorption capacity than glycol, the capacity (width) of the heat sink can be smaller. This offers advantages such as requiring a smaller pump to circulate the refrigerant around the system and a lower resistance so that less energy to operate the fan is necessary. Depending on the situation, a smaller-dimensioned fan may be sufficient. Direct vaporisation of the refrigerant in the heat sink also utilises the surface of the sink more effectively and gives a faster response to control measures than is the case with glycol. However, the most significant energy savings are delivered by the free cooling, or winter operation, an effect that can already be benefitted from with a direct vaporising refrigerant from an external temperature of 8°C and lower. Free cooling enables the same control options as conventional cooling mode, the difference being that in this situation the compressors are not active. This form of control is also possible with a glycol system, but at lower temperatures (roughly from an external temperature of 0°C and below). In the Netherlands, outside temperatures below 8°C occur with relative frequency, which enables the compressors to stop operating thereby saving significant amounts of energy. The correct switch-over point for free cooling can be set and regulated automatically depending on the external temperature.
Chilling Supermarkets not only demand produce that has been grown sustainably, they also want top quality mushrooms. They also increasingly request stag- gered delivery, meaning that growers have to store their produce for longer. Longer storage equates to longer cooling and higher energy costs. Longer storage also has a negative effect on mushroom quality. The possibilities of longer storage and the energy use this requires partly depend on the chil- ling method used. The classic chilling method is the familiar vacuum technology. This method has been used for decades to chill mushrooms post-harvest. However, vacuum chilling also results in moisture loss that can add up 15%. Moisture loss leads to a lower weight and poses a risk of lower quality both of which have a detrimental impact on the price. Cofely Refrigeration BV from Panningen ran a chilling trial on a mushroom farm based on a new version of a direct pump system. The investment in this system is even more financially interesting than in traditional vacuum cooling technology. During the trial, the mushrooms were chilled in a short period with a minimum of moisture loss. The trial results indicated that the moisture loss was limited to a maximum of 3 %. The volume remained largely unal- tered, and there was no discoloration either. Even after a five-day storage period, a minimum of quality loss was noted. This trial seems to herald the arrival of a new alternative to chill mushrooms. Linking the systems to chill the harvested mushrooms and to cool the growing mushrooms is also possible, which gives added advantages in terms of investment costs and heat recovery to warm the growing rooms. ◗
“For the complete
Mushroom Package”
JFM Growing Structures . Fancom Computer Controls . Air Handling Units . Climate Control Equipment . Hato High Frequency Lighting High Pressure Humidification Shelving and Equipment . Growing Nets Casing Nets . Tunnel Nets
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44
