TY JOUR TI SIMULATION MODEL OF HEAT PUMP EQUIPMENT OPERATION IN HEATING SYSTEM IN THE CHELYABINSK REGION CONDITIONS KW heat pump KW low-potential heat energy KW direct field experiment KW simulation modeling JO Bulletin of KSAU AU Nizamutdinov, R.Z. AU Ptashkina-Girina, O.S. AU Doskenov, A.K. PY 2013 IS PB Krasnoyarsk State Agrarian University