How to choose the right freezer

How to choose the appropriate freeze dryer 1, freeze-dried area freeze-dryer model of the number represents the type of freeze-dried machine freeze-dried area, users should according to their own needs, through calculation to determine how much freeze-dried area to use the freeze-dried machine.
e.g. each batch of products requiring 1.8 kg (L) of liquid, material is loaded with a pallet, each plate is loaded 10mm thick, the load area of the freeze-dried plate layer can be calculated: A (area, m2) - V (volume, m3)/H (height, m) s 0.0018m3/0.01m s 0.18m2 is required to select a freeze-dryer with a plate load area of 0.18m2.
2, cold trap temperature cold trap is the frozen drying process to capture moisture device, theoretically speaking, the lower the cold trap temperature, cold trap water capture capacity is stronger, but the cold trap temperature is low, high refrigeration requirements, machine costs and operating costs are high.
Cold trap temperature of -50 degrees C freeze-dried suitable for some easy freeze-dried products, cold trap temperature of -60 degrees C or so freeze-dried machine suitable for most products freeze-dried, cold trap temperature of -80 degrees C freeze-dried suitable for some special products freeze-dried.
the effect of cold trap temperature on water capture capacity showed that the cold trap temperature decreased from -35 degrees C to -55 degrees C, the water catching capacity was significantly improved, the cold trap temperature was lower than -55 degrees C, and the water catch capacity of cold traps was not significantly improved.
, in the absence of special needs, the choice of cold trap temperature of around -60 degrees C is ideal.
and the use of mixed-quality refrigeration technology, in the same refrigeration unit, the refrigeration temperature is low, the cooling capacity is large, the operating stability is high, the failure rate is low.
3, cooling rate cooling rate reflects the refrigeration capacity of the refrigeration system, in the case of empty load, the cold trap temperature should reach the target of Z low temperature within 1 hour.
example, a freeze-dryer with a cold trap temperature of ≤-60 degrees C, the machine starts to time from the start of cooling, and the cold trap temperature reaches -60 degrees C for no more than 1 hour.
4, the limit vacuum degree extreme vacuum degree reflects the leakage of the freeze-dryer and the pumping efficiency of the vacuum pump.
the vacuum of the freezer, the old view is that the higher the better, the current view is that the vacuum should be within a reasonable range.
vacuum is too high, is not conducive to heat transmission, drying speed is decreasing, but in any case the freeze-dried box load limit vacuum should reach 15Pa below.
5, vacuum time freeze-dried box empty pumping speed, should be within half an hour from the atmospheric pressure to 15Pa.
6, plate temperature uniformity and flatness: plate temperature uniformity and flatness, the homogeneity of product quality has a great impact, temperature uniformity and flatness is better, then freeze-dried product quality uniformity is also the better.
frost dryer shelf temperature control has a heater type and intermediate fluid type, the use of intermediate fluid control board layer freeze-dryer shelf temperature uniformity and flatness is good, this freeze-dried machine board layer is hollow mezzanine structure, plate layer cooling and heating are through the intermediate fluid in the fluid channel circulation within the plate layer to achieve, so the plate layer temperature is uniform.
the shelf temperature control of the bell cover freeze-dryer is basically using a heater, and the temperature consistency of the plate layer is slightly worse.
overall, however, the temperature difference of the plate layer for medical use should be controlled at ±1.5 degrees C, the temperature difference within the plate is ± l degrees C, and the food freeze-dryer can be appropriately relaxed.