How much is the approximate monthly or annual alimon for a wife who did not conceive, in order to pay for the alimon of a marriage that lasted two years and four months?

It is not a condition that the wife's maintenance be in the form of money; rather, what is obligatory is to provide her with sufficient food, housing, and clothing in a manner that is appropriate for the circumstances of both spouses. So, if you provide your wife with her sufficiency in these matters according to what is customary, then you are not obliged to give her money as compensation for maintenance.