Holding the hammer he took from the workbench, Chen Xin hammered the ice in the bunker one by one, and couldn't help panting tiredly.

Leaning on his waist, Chen Xin leaned against the wall in the bunker and took a deep breath, although the oxygen content in the shelter has not been low because of the existence of oxygen concentrators and planting greenhouses, but this position can actually be regarded as the outside world, after Chen Xin de-iced just now, he couldn't help but feel short of breath and couldn't breathe.

Reaching out and taking out an oxygen cylinder from his pocket, he opened the protective mask on his face, and took a few sips into his mouth and nose.

"Whew, when does this have to knock on the head!" Chen Xin couldn't help but sigh with emotion, after the ice was thick, it was not something that the small hammer in his hand could move at all, and if he smashed it hard, he would knock some ice slag down.

This inevitably made him feel a little frustrated, de-icing is not an easy job, this is not like shoveling snow, how can it be cleaned up with a shovel.

However, ice, especially frozen ice, is very difficult to clean, and in the past, if it was frozen, the snow and ice would not melt until the beginning of spring.

But now Chen Xin can't wait for the temperature to rise and the spring flowers bloom, and the ice melts by itself, so he must find a way to remove the ice in front of him, which is at least 30 centimeters thick.

To be honest, he had expected ice accumulation, and he knew that it would be more serious if he didn't accumulate ice for a few days, but he didn't expect the ice to be a foot thick.

With such a thick layer of ice, even if you use a professional ice axe and iron fiber, it is difficult to clean it up with a sledgehammer, not to mention that Chen Xin only has a small iron hammer in his hand.

He took the hammer and smashed it a few more times on the ice, but it seemed to have an effect, except for a little crushing ice slag, there was not even a crack on the ice.

This made Chen Xin frustrated, and lamented in his heart, if there was any way to solve the ice accumulation at one time, it would be better if he could further and completely solve the ice accumulation problem here at the vent.

It's just that how easy it is to solve the problem? Chen Xin smiled bitterly, and smashed it on the ice with a hammer.

While smashing, Chen Xin was also thinking about how to solve the problem of ice accumulation.

The main reason for the formation of ice accumulation is that the air blown out of the shelter by the vent contains water vapor, which quickly condenses and sinks when it is cold, and freezes into ice before it flies out, and then accumulates here.

This can be seen from the fact that Chen Xin knocked on the ice for a long time, and the surface of the protective clothing on his body was frozen.

Patting off the ice on the surface of the protective suit, Chen Xin sighed, although he knew the principle, but it was not a matter of upgrading the ventilation system to remove the moisture from the air blown out of the vent.

If he wants to remove moisture from the air, Chen Xin does know the method, that is, air drying, but this is mainly a technology used in industrial production, and it is too wasteful to use it for the ventilation and exhaust of the shelter, and the consumption is also large.

Therefore, in Chen Xin's vision, it is enough not to freeze in the small bunker.

In this case, improving the ventilation form of the exhaust vents, or adjusting the structure of the bunker to change the vents to the outside, can also solve the problem.

But Chen Xin was a little reluctant to change the vent to the outside, because in that case, the air temperature blown out of the vent would be significantly higher than the ambient temperature, although it could not be seen with the naked eye, but with an infrared telescope, this vent would be as conspicuous as a searchlight in the night.

And although the vent is not as easy to climb in as it is in European and American movies, it will still cause a lot of problems if it is discovered.

Now put it in a small bunker, although there is a possibility of being discovered, but it is still much less dangerous.

So to solve the problem, it is best to find a way to make the water vapor freeze without freezing in the bunker.

Chen Xin pondered for a long time, and suddenly smashed down with a hammer, and a flash of inspiration in his mind finally opened his mind.

"I'm really stupid at home, it's not over with a system upgrade!" Chen Xin slapped himself on the head violently, secretly annoying that his mind was confused after staying with Qin Lan these days, and he didn't think that he could still use system upgrades to solve the problem.

Chen Xin called out of the system interface, glanced at the survival point that had accumulated to four figures, and had enough confidence in his heart.

These survival points were prepared by Chen Xin in order to upgrade the shelter as a whole, and he consumed some points when he made the ground source heat pump before, but he was not at home these days, but the survival points obtained every day were not less, and the daily survival point income of nearly 40 points made it easy for him to come up with the survival points of the transformation and upgrading of the small bunker.

"The Humble Observation Room"

"Upgrade plan 1: increase the area of the observation room, improve the building structure, increase concealment and air permeability, enhance the signal reception capacity of the shortwave antenna, and upgrade the required survival point 700"

"Upgrade plan 2: improve the defense capability of the observation room, improve the strength of the building, increase the thermal insulation protection performance, increase the protection of the observation port, and upgrade the required survival point 1100"

Both upgrade plans are not very cheap, and the focus is still different, but because of the lack of building materials, and the existing materials are prepared for the overall upgrade of the shelter, Chen Xin did not use the method of upgrading both.

After comparing the two options, he still chose to spend 700 points to upgrade the first plan, that is, the option to enhance the concealment and ventilation performance of this small bunker, and at the same time improve the signal reception ability of the shortwave antenna he installed here.

Although Chen Xin also wanted the second plan, he couldn't consume too many survival points, and after hesitating for a while, he still gave up this upgrade option that obviously evolved the small bunker in the direction of the bunker.

After the upgrade, the area of the small bunker has increased a bit, and the overall appearance is a perfect circle, but it has not expanded too much, and the observation port is still the same as before, and has not changed.

It's just that the original vents in the room have become ventilation ducts buried in the walls, which will be ventilated through the façade of the exterior wall of the small bunker.

This is obviously a perfect solution to the problem of ice accumulation in the room of the vent, and because the ventilation pipe goes from the outer wall of the observation room, the air coming out of the vent will first lower the temperature in the ventilation pipe and then discharge, which is not so obvious from the infrared perspective.

For this, after the upgrade was completed, Chen Xin came out of the gate of the shelter and used the infrared vision function of the tactical eyepiece to observe the location of the observation room, and indeed he could not see the traces of the air discharged from the vent.