Refrigerant 134a at 1 MPa and 90oC is to be cooled to 1 MPa and 30oC in a condenser by air. The air enters at 100 kPa and 27 oC with a volume flow rate of 600 m3/min and leaves at 95 kPa and 60oC. Determine the mass flow rate of the refrigerant. [R=0.287 kPa. m3/kgK][Use specific heat values at room temperature].

Amajor impediment to wide acceptance of electric vehicles even on the part of people who use their cars almost exclusively for commuting is the inability to use their electric vehicles for occasional extended trips. in an attempt to make purchasing electric vehicles more attractive to commuters, one electric vehicle producer is planning to offer customers three days free rental of a conventional car for every 1,000 miles that they drive their electric vehicle. which of the following, if true, most threatens the plan's prospects for success? (a) many electric vehicles that are used for commercial purposes are not needed for extended trips. (b) because a majority of commuters drive at least 100 miles a week, the cost to the producer of making good the offer would add considerably to the already high price of electric vehicles. (c) the relatively long time it takes to recharge the battery of an electric vehicle can easily be fitted into the regular patterns of car use characteristic of commuters. (d) although electric vehicles are essentially emission-free in actual use, generating the electricity necessary for charging an electric vehicle's battery can burden the environment. (e) some family vehicles are used primarily not for commuting but for making short local trips, such as to do errands.