Update 2021-09-07-design-of-the-koji-room-koji-muro.md

I added a diagram of a simpler koji room for use as a thumbnail. Let me know if that works

Author: daizu27

_posts/2021-09-07-design-of-the-koji-room-koji-muro.md

@@ -1,7 +1,7 @@
 ---
 title: Design of the koji room (koji-muro)
 author: keith
-image: assets/images/koji_room/Wallheattransfer.png
+image: assets/images/koji_room/kojiroomthumb.png
 ---
 
 I hope this post will provide a bit of guidance to anyone trying to build a koji room (also known as the *koji muro* or *sei-kiku shitsu*), especially as they scale up to the 50-1500kg/batch range. I'll go into the details of the history, design, and operation of the koji room.