The cooling produced by melting of 1 ton of ice in a day is 
taken as unit of refrigeration (in tons). Now unit of 
refrigeration used in S.I. System is KW.
 1 ton of refrigeration 
= mass of ice x latent heat of ice / 24 hrs 
   
= 900 kg x 335 KJ/Kg         ( one short ton = 900 kgs )
  ------------------
    24  x 3600 secs
= 3.4895 KJ/Sec
say 3.5 KJ / Sec = 3.5 KW

that is 1 ton of refrigeration = 3.5 KW