Not strictly plumbing, but definitely a heating problem...
A client has a butcher's shop with an 8' x 8' freezer, this freezer rejects heat via a condenser on the flat roof above. Generally speaking it runs 24 hours per day on about a 20% duty cycle. (Season dependant)
With the freezer blowing warmer air than ambient across the roof it seems like a good place to put an ASHP evaporator which will feed 3 blowers inside the shop/office/kitchen (a split system). The rejected heat from the freezer will help to 'recycle' energy into the warmed places in the shop, thus reducing the overall energy consumption - a green project.
The problem I envisage is trying to synchronise the running of the ASHP to the running of the freezer condenser fan. The freezer runs in start-stop mode, so fan speed modulation is not an option (ie running the freezer 80% of the time at 25% load). At present the only solution I can think of is to interface the ASHP compressor with the freezer fan, allowing the 3 room fans to blow colder when the freezer isn't rejecting heat.
Does anyone have any brighter ideas that won't significantly add to the cost?
One suggestion is to incorporate a liquid 'heat store' between the two devices, the freezer output warming this buffer store, the ASHP taking that heat over a longer timeslot; this seems feasible but adds more complication than I'd like.
Another consideration is that the output of the freezer must not be severely compromised by restriction to the heat rejection airflow...the contents of a large meat freezer are far more valuable than a few kW of green energy.
Are there any problem solvers out there?
MM
A client has a butcher's shop with an 8' x 8' freezer, this freezer rejects heat via a condenser on the flat roof above. Generally speaking it runs 24 hours per day on about a 20% duty cycle. (Season dependant)
With the freezer blowing warmer air than ambient across the roof it seems like a good place to put an ASHP evaporator which will feed 3 blowers inside the shop/office/kitchen (a split system). The rejected heat from the freezer will help to 'recycle' energy into the warmed places in the shop, thus reducing the overall energy consumption - a green project.
The problem I envisage is trying to synchronise the running of the ASHP to the running of the freezer condenser fan. The freezer runs in start-stop mode, so fan speed modulation is not an option (ie running the freezer 80% of the time at 25% load). At present the only solution I can think of is to interface the ASHP compressor with the freezer fan, allowing the 3 room fans to blow colder when the freezer isn't rejecting heat.
Does anyone have any brighter ideas that won't significantly add to the cost?
One suggestion is to incorporate a liquid 'heat store' between the two devices, the freezer output warming this buffer store, the ASHP taking that heat over a longer timeslot; this seems feasible but adds more complication than I'd like.
Another consideration is that the output of the freezer must not be severely compromised by restriction to the heat rejection airflow...the contents of a large meat freezer are far more valuable than a few kW of green energy.
Are there any problem solvers out there?
MM
