It is called Visbreaking. As a result, initial fluid is separated into lower viscosity liquid and sludge. Sludge causes problems in pipe-lining of hydrocarbons.
The main application of liquefaction is the production of liquid and solid carbon dioxide and liquid nitrogen. In cogeneration systems, using several small compressors instead of just one large compressor is possible to obtain thermal energy and drecrese the energy used in compression system.
Liquefaction produces bio-oil mainly where as pyrolysis produces mixture of bio-char, bio-oil and syn-gas. Considering energy balance between liquefaction, combustion and pyrolysis, liquefaction may be the low energy demanding.
GTI has the IH2 process which produces a viable liquid transportation fuel with minimal upgrading requirements. But your question is really asking for a comparison of apples and oranges. If you are not making the same products what does such a comparison mean. Does a combustion process satisfy the need for transportation fuels? If what I want is heat and power how does a pyrolysis process satisfy that energy demand?
As I know to-day really there is only one operating system for such of waste tire liquefaction processing in China, being me informed on that also as much early in 2002-2003 in Russia. The process is concluded in tire dissolving with used oil, performing that at the pressure and temp as all of that is presented in the attached file. But I think the singularity of such system is a good evidence of not opportunities but complexities of that.