Greetings, and thanks for taking a look. Here’s the scenario: I’m working with a group of college students to design a batch plastic recycling system for recycling water sachets that litter the streets in developing countries (http://www.travelblog.org/Photos/65115.html). One of our unit operations is the melting of the shredded/cleaned HDPE plastic. We have a parabolic solar cooker for heat (this thing gets hot!). We need to keep our melting pot / system at 160 C - the cooker gets temperatures much higher than that. We are working on a propylene glycol/water bath that would boil at 160, and keep our melting pot at the same temp. We would recirculate condensate so that we can keep the PG. However, PG is expensive, and has the potential to not be available in pure (and safe) form in some countries. We’ve bounced the idea of pressure-regulated steam around, but don’t want to design a potential explosion.

Anyone have some ideas on how to keep our melting pot temp at ~160 without using dangerous chemicals/expensive equipment? Thanks!