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Q)
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What types of evaporators (coolers) can you supply?
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A)
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We can supply a wide range of evaporators for all applications,
including coldrooms, beer cellars, blast freezers and liquid
cooling.
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Q)
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When do you fit an external equalised expansion valve?
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A)
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If the evaporator (cooler) has a distributor an external
equalised valve should be fitted. A typical distributor by
design could have a pressure drop of 20psi (1.4bar). Sensing
the pressure on the outlet side of the evaporator compensates
for the pressure drop through the distributor. If not used
the evaporator will be starved of liquid, with lose of duty.
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Q)
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What is the significance of the t.d. (temperature difference)
across an evaporator (cooler)?
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A)
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The t.d. affects the amount of moisture extracted during
the refrigeration process and consequently can affect the
product being stored.
For example, when cooling plants or vegetables a td of 4
C is typical to keep the room humidity up and to stop the
product being dried out. A low air velocity cooler should
be also used to stop product dehydration.
If a product has to be cooled down from a higher temperature
a td of 7 C can be used to help draw the heat from the product.
Normally the product would be packed to prevent moisture loss.
Also a high air velocity cooler should be used to help draw
the heat.
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Q)
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What type of evaporator (cooler) can you supply for cooling
liquids?
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A)
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We can supply fully brazed plate heat exchangers (BPHEs)
for cooling water, glycol solutions or oil using HFC or HCFC
refrigerants, and also a range for NH3 (ammonia). These are
constructed from specially formed stainless steel plates brazed
together with 99% copper (the copper is plated for use with
NH3). Ideally suited for cooling liquids down through 5 C.
BPHE's can also be used for condensers, de-superheaters and
sub-coolers please contact our Engineering dept for details.
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