I have been trying to increase the humidity of my thermal chamber by putting water inside the chamber and increasing the Temp up to 40 degrees but I have not been able to increase the humidity. can anyone suggest a solution
An ultrasonic nebulizer has worked well for me in similar situations.
Or, have an external 'pot' (I used a small pressure cooker) and deliver a small flow from that via a blower into the main chamber. Use a hygrometer to control the blower, and that ought to readily raise your RH without warming the chamber air too much.
I'm not surprised that merely sitting a tray of water in the chamber didn't achieve the desired result. You might try an atomizer or mister of some sort. There are shelves full of spray bottles at any grocery store. You can get a vaporizer at any pharmacy.
spray the water to very fine droplet with low rate at high cone angle to be mixed with environment and until be evaporated.