Vavu yowonjezera ndi gawo lofunika kwambiri la firiji, lomwe nthawi zambiri limayikidwa pakati pa silinda yosungiramo madzi ndi evaporator. The valavu kutambasuka zimapangitsa madzi refrigerant pa sing'anga kutentha ndi kuthamanga kwambiri kukhala chonyowa nthunzi pa kutentha otsika ndi kuthamanga otsika kudzera throttling ake, ndiyeno refrigerant zimatenga kutentha mu evaporator tikwaniritse refrigeration kwenikweni. Valavu yowonjezera imayendetsa kayendedwe ka valve kupyolera mu kusintha kwa kutentha kwapamwamba kumapeto kwa evaporator kuti ateteze kusagwiritsidwa ntchito bwino kwa dera la evaporator ndi chodabwitsa cha kugogoda kwa silinda.
Mwachidule, valavu yowonjezera imapangidwa ndi thupi, phukusi lozindikira kutentha ndi chubu lokwanira
Malo abwino ogwirira ntchito a valve yowonjezera ayenera kusintha kutsegulira mu nthawi yeniyeni ndikuwongolera kuthamanga kwa kuthamanga ndi kusintha kwa evaporator katundu. Koma kwenikweni, chifukwa cha hysteresis ya kutentha kwa kutentha mu envelopu yowona kutentha, kuyankha kwa valve yowonjezera nthawi zonse kumakhala pang'onopang'ono. Ngati tijambula chithunzi cha nthawi ya valve yowonjezera, tidzapeza kuti si njira yosalala, koma mzere wa wavy. Ubwino wa valavu yowonjezera ukuwonekera mu matalikidwe a mafunde. Kukula kwa matalikidwe, kuchedwetsa kachitidwe ka valve ndi khalidwe loipa kwambiri
