Modeling Munters ERV in Equest

2 posts / 0 new
Last post

The Munters unit I am using is the Drycool Dehumidification System. It is a 100% OA unit that I am using to feed several water source heat pumps room neutral air thus lowering the load on the heat pumps. Outside air enters the Munters unit and passes through the top half of an Enthalpy wheel. Return air from the space passes through the bottom of the wheel exchanging heat from one stream to the other. The outside air is then pre-cooled with a DX coil then passes through a desiccant wheel. The DH wheel is regenerated with the same return air stream as before after is has passes through a row of coils with heat from the compressors. The supply air is now 76? 33% RH. That air is then ducted to return plenums attached to each heat pump.

I know that I can use the "Outside air from system" option to supply the air to the heat pumps but I have yet to find a way to accurately model this unit, specifically the enthalpy wheel's position in the system and the desiccant wheel's regeneration source (waste heat from the compressor). Admittedly I a new to equest but I have spent a considerable amount of time on the conundrum. Any help would be greatly appreciated.

Kyle B. Keith

Kyle Keith's picture
Joined: 2011-09-30
Reputation: 0


Im not familiar with Munters, but Im modelling a similar type of system using a Daikin Desica ERV here in Japan. The difference being that rather than an enthalpy wheel, the Desica has a multi-chamber crossflow HX with solid desiccant section. Rather than preheating exhaust air to regenerate the desiccant, the hot gas coils are actually imbedded in the desiccant for direct contact heating. There's a control damper that switches air flow from between the usable desiccant and desiccant undergoing regeneration sections.

I don't know of anyway to "accurately" model this system, but I am attempting to get a decent estimate given the limitations of the software. I doubt this is the magic bullet, but I'll explain what I'm doing:

I think you have to use the OA from system command to pull this off. I set up a dummy zone with a CAV PSZ heat pump unit with solid desiccant pre treat and heat recovery. Make sure to get your supply temp dialled in, latent/sensible cooling capacity of your coils and don't double count your fan power. Set OA to 100% and your RH setpoint.

The "waste heat from compressor" issue is something that has driven me nuts for awhile since there appears to be no way to recover heat off the compressor for a heat pump in eQuest. Also, you need to reconcile if this is always going to be waste heat in the sense that will the heat pump ever operate primarily to regenerate desiccant or will it always be cooling first. Basically I have come to 2 options

1) Assign gas hydronic for regeneration. Define submeters for heat pump check your btuh hourly demand for gas and compare with hourly heat pump load. My assumption is that as long as the cooling load on the unit is greater than btus required for regeneration then regeneration is always waste heat and can be discounted, i.e. ignore the gas usage in your result reporting.
2) This something that I am still toying with but it seems to work in principal. Build an air cooled heat pump chiller with compressor heat recovery (compressor heat recovery only seems to be available for chillers in eQuest). Assign the PSZ as a chilled water system and assign the desiccant regeneration to be hotwater off of your chiller. Discount and water pump energy for your water loops and make sure your performance curves are dialled into mimic your heat pump.

I would be interested to hear if anyone has tried anything similar or has comments on the above.


Shuichi Hendrickson

Shuichi Hendrickson's picture
Joined: 2011-09-30
Reputation: 0