This is good. 3M also has heat transfer fluids called HFEs that are much less harmful. They can also be used as heat recovery fluids for getting more out of ICEs with expansion scrolls and turbines.
Since 70% of the energy in ICEs is rejected heat, there is work to be done there.

Harvey D. -

in theory, the heat transported by the coolant (of similar magnitude as that delivered by the crankshaft) could be used to power an absorption chiller. These devices use a combination of two substances that are miscible in any proportion, one of which will evaporate almost completely out of the solution well before significant amounts of the other do. The most commonly used systems are H2O-NH3 (lowest achievable temps ~ -60 deg C) and H2O-LiBr (a salt; lowest achievable temps > 0 degC). As with any refrigeration technology, the lower your chiller temp, the more input energy you need to achieve it.

The clue here is that this energy comes in the form of heat plus a negligible amount of electricity for a flow pump, rather than valuable mechanical work. Absorption chillers have a much lower coefficient of performance (COP, indicating cold energy produced vs. input energy) of 0.7-1.1 for single-stage units with internal heat exchanger. For comparison, the COP of a traditional R134a chiller is about 3, but that goes back down to 1-1.5 when you include the losses in the dedicated engine/electric power used to drive the compressor.

Since absorption chillers are substantially more expensive to construct, they really only make sense if you have a reliable stream of low-grade waste heat or, if spot prices for your input energy are highly volatile (e.g. wholesale electricity in the summer in California). In a vehicle powered by an ICE, there is of course abundant waste heat, both high grade (exhaust gas) and low grade (engine coolant). While you can use the former to drive a turbocharger, turbocompund, pressure cell booster or thin-film thermoelectrics, the latter is only useful for space heating and via absorption chillers, for cooling.

Note that in large diesel engines, there are additional sources of heat from the intercooler and the EGR cooler. You could use these plus the engine coolant to not only provide a/c for the driver cabin/passenger compartment or cargo hold but also to interchill the fresh charge. The device would be located between the intercooler and the intake manifold. As long as you don't run into condensation and ice formation problems, reducing the intake temperature by an additional 30 Kelvin (about 10% in absolute terms) will let you achieve the following: higher thermodynamic efficiency, increase specific power at the same peak process temperature and/or sharply reduce peak process temperature (and hence, engine-out NOx levels) at the same specific power level.

Unfortunately, there are a number of technical reasons absorption chillers are not currently being used even in large vehicles such as cruise ships, trains, buses and refrigeration trucks:

(a) The traditional design of the absorber component is based on a fine falling mist of lean solution. This has been proven highly sensitive to vibrations and hence unsuitable for mobile applications. A promising new approach based on more robust and compact membrane absorbers is being developed in Germany:

http://www.itt.uni-stuttgart.de/~schaal/index.en.html

(b) Vehicles may be parked in freezing temperatures. Any pure water in any part of your system is likely to cause some burst pipes. This pretty much rules out the cheaper LiBr route, which relies on water as the refrigerant. The NH3 route is viable but sealing is essential as ammonia is toxic at concentrations at which you can smell it. That immediately raises a crash safety issue as well (imagine an injured person unable to free themselves from the wreckage subjected to ammonia fumes)

(c) An aborption chiller system require a minimum of 4 heat exchangers, compared to 2 for a traditional a/c unit. These require space and add weight to the solution.

(d) the dynamic response of absorption chiller systems is relatively poor compared to traditional a/c. Moreover, chiller power is constrained at low engine loads. This would be a problem if you were caught in a traffic jam in the middle of summer. Excess ambient temperatures, especially near the head, tend to reduce driver attentiveness and increase aggressiveness, so vehicle a/c is a safety as well as a comfort issue in hot weather. Low chiller power during rest periods for the driver is also problematic for cargo refrigeration applications.

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Could some of the ICE important wasted heat energy be economically converted to operate the vehicle HVAC (including the AC + electronic + electrical gadgets etc)?

Secondly, if wasted heat is recovered to operate other on-board support sub-systems, could the main ICE engine be down sized proportionally?
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BMW is planning on this to augment the power output of future models. I think the article was on this site in the last week or so.

What happened the idea of using a CO2 based A/C system? Seems like Toyota was working on a system that would heat or cool. Last time I saw any mention was here on GCC some several months ago. I wonder if the use oc CO2 would be seen as a way to consume some of the excess in our enviroment or as another potential source of emmissions?

Harvey D. -

well, turbochargers and for HDVs, mechanical turbocompounds, are very feasible today, for both gasoline and diesel engines. There are also R&D projects on electric turbocompounds, both standalone (TIGERS) and as electrically assisted turbochargers/generators. Thermoelectrics are also progressing, though they are not a near term prospect for mass production. All of these leverage the high-grade waste heat.

Power-centric hybrids can recuperate the kinetic energy of the vehicle via recuperative braking. Storage systems include ultracaps, hydraulic accumulators and, in theory, pneumatic accumulators.

What no-one has done so far is leverage the waste heat in the coolant for anything other than space heating. Absorption chillers would be one option.

There have been attempts to increase the coolant (not necessarily water) pressure in the engine yielding wet steam. This is then superheated by a heat exchanger in the exhaust, to drive a small radial steam turbine, which is mechanically connected to the crankshaft via a CVT. The spent steam is condensed in a radiator and the water re-pressurized. BMW engineers call this co-generation concept "turbosteamer" but it is still far from market-ready. On big problem is that a lot of the heat scavenged from the exhaust gas needs to be lost via the radiator. The cross-sectional area of a car's engine compartment is limited and placing the radiator at a severe angle typically not possible.

I like a Stirling cycle heat pump system. Even dry air could be used as the working fluid.

Jason,

I haven't heard of CO2 cooling for passenger vehicles, but AFAIK it's beginning to see commercial use in e.g. grocery stores and and delivery trucks for frozen goods etc.

One of the main reasons for the interest in CO2 is in fact the environmental benefits. The amount of CO2 emitted in regular power production is so huge that a small amount of leakage in cooling systems is completely insignificant in comparison. And indeed, AFAIK industrial CO2 is gathered from exhaust gasses that otherwise would go straight into the sky, so no net global warming. But compared to "classical" refrigerants like R12 or R134, CO2 is nontoxic, nonflammable and non-ozone depleting.

I was thinking of a fluid to fluid tube in tube heat exchanger for the cooling system and then to fluid cooling for the exhaust headers as a "topping" cycle before the scroll. Whether you drove the engine with a scroll and belt or just had the scroll drive an alternator would be an application issue, maybe both. It sure sould be nice to recover some of that rejected heat.