Dry cooled heat exchanger to cool water at higher ambinet

If you don't have a sink for your heat you'll need a heat pump.

By "dry cooling" do you mean an air cooled HX?

If your cooling air is 52C, then no, a straightforward fin fan cooler will not reach 45 C of the water. Probably the best you can practically get is 58 to 60C in that air temp.

You need some sort of chiller unit but the fin fan cooler might be able to do most of the work depending on your arrival temperature

Or accept a higher demin temperature on those really hot days.

Or accept only running it over night when the air cools to less than 40C.

Someone else here was talking abut using liquid Nitrogen to cool his fluid, but that sounds v expensive to me.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

There are many other ways of getting demin water temp down to 45degC, but it will involve more equipment and a keen eye for some new process route to harness the waste heat that may be going up the stack at the moment in your plant or the compression energy that may be going to waste.