Yes. I used a window cooler just like the one you picture last year. Set it on the ground pointed into the back door of my 6 by 10 tent type GH. Blocked the rest of the door except for a space at the top. Had a cardboard cover over that that would hinge out when needed. Worked great in our 100 degree Colorado sunshine. Only problem was the garden hose I had to supply it kept blowing up from the pressure and hot sun. It was listed as a "3000" unit and it needed to be on "high" on the hottest days.
PS, the plastic pads are worthless, make sure you have the wood type ones. Remember this is in dry Colorado.
Go for it, KennyP

Thank you for the input! I've heard that the plastic pads can be pretty bad. I would prefer cellulose pads, but they don't seem to make window units with cellulose pads. Did you have any trouble with the aspen pads?

They only work well when the humidity is low enough, and in Minnesota I have my doubts about them making much difference. The relative humidity and the temperature are what controls how cool the air coming out of the unit will be.

"while the portable type would be used inside throughout the rest of the year"

That doesn't work well. The air gets saturated and you don't get a drop in temperature after a few hours. You end up with a hot, humid jungle.

*********
You will probably get better results from vents and shade cloth.

There's a commercial greenhouse here that uses a wetwall which works very well. The owner also recommended an evaporative cooler, so I think the humidity drops enough during the day when you really need the cooling.

As for the portable cooler, I'd be using it for a bit of cooling in the spring and fall, but mainly for maintaining humidity the rest of the year. Otherwise I have to wet the greenhouse floor every 20 minutes to maintain any decent humidity level. I've also been considering a Hydrofogger or other greenhouse humidifier to use the rest of the year. I'm not sure what would be best for maintaining humidity without wetting plants and walls.

At one time the farm stores sold what they called misters, which were very fine spray nozzles. they used them to keep hog operations cool.

How about a timed mister aimed at the floor?

I considered that, but there are times when even frequent hand misting won't get the humidity high enough. I think I'll end up getting one of the window units this spring, and then I'll consider a humidity solution next fall when I have to take down the window cooler.

We installed a swamp cooler "evaporative cooler" in our newly constructed greenhouse. So far, it is working great. My plants are happy and everything isn't getting boggy from excessive water to cool it down.

The window evap cooler units are not as efficient as a wet wall on one end and exhaust fans on the other end. Mine has the later and I can keep it as cool or cooler inside than out. Today was an extreme example 100F outside which gave about 68F out of the wet wall and a high of 85F on the exhaust, hot end. With much higher dew points in summer it's still as cool inside as out with no shade cloth.

The window evap units are inefficient because they mix the cool air with the hot inside and a mixture of that leaves the house. With exhaust fans pulling the cool in, the hottest driest air is pulled out.

I think an efficient evaporative system would still be a huge help in MN. Much better than anything mentioned above. A shade cloth, if you can stand lower light levels, is an additional considerable help.

I'm growing all kinds of fruit in a greenhouse in SW Texas without shade cloth. The crops do very well and fruit quality is very high. But most of these crops are OK at 90F high temperatures.

Greenhouses with efficient evap cooler systems are used to grow tomatoes most of the summer in central TX where it is hotter and more humid than here, upper 90s highs and 70F dew points. You should be able to grow almost anything in summer in MN.