MEBS6008 Heat Pump

7/25/2019 MEBS6008 Heat Pump

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Heat Pump 1

MEBS 6008

Heat Pumps


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Heat Pump 2

A heat pump is a self-contained, packaged cooling-and-heating unit with a

reversible refrigeration cycle.

A heat pump is basically a devicethat transfers heat from one substanceto another substance.

It has these same basic refrigeration components: compressor, condenser,

evaporator, and expansion device.

he difference is that it can also reversethe refrigeration cycle toperform heating, as well as cooling, by reversing the functions of the twoheat exchangers.

he operation of the refrigeration cycle changes depending on whetherthe unit is in cooling or heatingmode.

Heat pump is generally reserved for e!uipment that heats for beneficialpurposes, rather than that which removes heat for cooling only.

What Is a Heat Pump?


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Heat Pump 3

Dualmode heat pumpsalternately provide heating or cooling.

Heat reclaim heat pumpsprovide heating only, or simultaneous

heating and cooling.

An applied heat pumpre!uires competent field engineering for

the specific application, in contrast to the use of a manufacturer-designed unitary product.

Builtup heat pumps#field- or custom-assembled from

components$ and industrial processheat pumps are two types.

What Is a Heat Pump?


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Heat Pump 4

%ost modern heat pumps use a vapor compression#modified&ankine$ cycle or an absorption cycle.

Although most heat pump compressors are powered byelectric motors, limited use is also made of engine andtur!ine drives.

Applied heat pump systems are most commonly used forheating and cooling buildings, but they are gaining popularityfor e""icient domestic and service #ater heating, poolheating$ and industrial process heating%

Heat Pump &'cles


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Heat Pump 5

'eat sources include the ground, well water, surface water,gray water, solar energy, the air, and internal building heat.

(re!uently, heating and cooling are supplied simultaneouslyto separate )ones.

*ecentrali)ed systems with water loop heat pumps are

common, using multiple water-source heat pumps connectedto a common circulating water loop.

hey can also include ground coupling, heat re+ecters#cooling towers and dry coolers$, supplementary heaters#boilers and steam heat exchangers$, loop reclaim heatpumps, solar collection devices, and thermal storage.

Introduction o" heat source and heat pump s'stem


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Heat Pump 6

(evie# o" a )'pical *apour &ompression &'cle

&efrigerant enters the evaporator in the

form of a cool, low-pressure mixture ofli!uid and vapor #I$.

'eat is transferred to the refrigerantfrom the relatively warm air or water tobe cooled, causing the li!uid refrigerant toboil.

he resulting vapor #II$ is then pumpedfrom the evaporator by the compressor,which increases the pressure andtemperature of the refrigerant vapor.

he resulting hot, high-pressurerefrigerant vapor #III$ enters the

condenser where heat is transferred toambient air or water, which is at a lowertemperature.

Inside the condenser, the refrigerantcondenses into a li!uid.


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Heat Pump 7

his li!uid refrigerant #I$ then flowsfrom the condenser to the expansiondevice.

he expansion device creates apressure drop that reduces thepressure of the refrigerant to that of

the evaporator. At this low pressure, a small portion of

the refrigerant boils #or flashes$,cooling the remaining li!uid refrigerantto the desired evaporator temperature.

he cool mixture of li!uid and vaporrefrigerant #I$ travels to theevaporator to repeat the cycle.

(evie# o" a )'pical *apour &ompression &'cle


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Heat Pump 8

where

h h/ 0 enthalpy of refrigerant entering andleaving evaporator, respectively,1 2kg

3in 0 work input, 12kghe coefficient of performance of the heatingeffect in a heat pump system 456hpis

A heat pump cycle comprises the same processes

and se!uencing order as a refrigeration cycleexcept that the refrigeration effect !/or !rf,

and the heat pump effect !78,both in 12kg, arethe useful effects.

Heat Pump &'cle


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Heat Pump 9

Basic t'pes o" heat pump c'cles+

&losed vapor compression c'cle

his is the most common type used in both 'A4 and industrialprocesses.

It employs a conventional, separate refrigeration cycle that may besingle-stage, compound, multistage, or cascade.


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Heat Pump 10

6rocess vapor is compressed to a temperature and pressuresufficient for reuse directly in a process.

9nergy consumption is minimal, because temperatures are optimumfor the process.

ypical applications for this cycle include evaporators#concentrators$ and distillation columns.

Mechanical vapor recompression c'cle #ith heat e,changer



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Heat Pump 11

A typical application for this cycle is in an industrial plant with aseries of steam pressure levels and an excess of steam at a lower-than-desired pressure.

he heat is pumped to a higher pressure by compressing the lowerpressure steam.

-pen vapor recompression c'cle



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Heat Pump 12

Heatdriven (an.ine c'cle

his cycle is useful where large !uantities of heat are wasted andwhere energy costs are high.

he heat pump portion of the cycle may be either open or closed, butthe &ankine cycle is usually closed.



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Heat Pump 13

5utdoor air is a universal heat-source and heat-sink medium for heatpumps and is widely used in residential and light commercial systems.

9xtended-surface, forced-convection heat transfer coils transfer

heat between the air and the refrigerant.

ypically, the surface area of outdoor coils is ; to /;;< larger thanthat of indoor coils.

he volume of outdoor air handled is also greater than the volume ofindoor air handled by about the same percentage.

*uring heating, the temperature of the evaporating refrigerant isgenerally = to // > less than the outdoor air temperature.

/ir

HE/) S-(&ES /1D SI12S


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Heat Pump 14

3hen selecting or designing an air-source heat pump, theoutdoor air temperature in the given locality and frostformation in particular must be considered.

As the outdoor temperature decreases, the heating capacityof an air-source heat pump decreases.

his makes e!uipment selection for a given outdoor heatingdesign temperature more critical for an air source heat pumpthan for a fuel-fired system.

he e!uipment must be si)ed for as low a balance point as ispractical for heating without having excessive andunnecessary cooling capacity during the summer.


/ir


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Heat Pump 15

3hen the surface temperature of an outdoor air coil is ;?4 or less, witha corresponding outside air dry-bulb temperature 7 to . > higher, frostmay form on the coil surface.

If allowed to accumulate, the frost inhibits heat transfer@ therefore,

the outdoor coil must be defrosted periodically.

he number of defrosting operations is influenced by the climate, air-coildesign, and the hours of operation.

It was found that little defrosting is re!uired when outdoor air

conditions are below /;?4 and =;< rh #confirmed by psychrometric

analysis$.


/ir


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Heat Pump 16

Bnder very humid conditions, when small suspended water dropletsare present in the air, the rate of frost deposit may be about threetimes as great as predicted from psychrometric analysis.

he heat pump may re!uire defrosting after only 7; min ofoperation.

he loss of available heating capacity due to frosting should betaken into account when si)ing an air source heat pump.

9arly designs of air source heat pumps had relatively wide fin

spacing of to = mm, based on the theory that this would minimi)ethe fre!uency of defrosting.

3ith effective hot-gas defrosting a much closer fin spacing ispermitted that reduce si)e and bulk of the system.

In current practice, fin spacing of /.8 to 7. mm are widely used.


/ir


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Heat Pump 17

4ity water is seldom used because of cost and municipalrestrictions.

Croundwater #well water$ is particularly attractive as a heatsource because of its relatively high and nearly constant

temperature.

he water temperature is a function of source depth and climate#Any information on water temperature of '>s situation D$.

(re!uently, sufficient water is available from wells for which thewater can be re-in+ected into the a!uifer.

he use is non consumptive and, with proper design, only the watertemperature changes.


Water


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Heat Pump 18

he water !uality should be analy)ed, and the possibility of scaleformation and corrosion should be considered.

In some instances, it may be necessary to separate the well fluidfrom the e!uipment with an additional heat exchanger.

Epecial consideration must also be given to filtering and settlingponds for specific fluids.

5ther considerations are the costs of drilling, piping, pumping, anda means for disposal of used water.

Information on well water availability, temperature, and chemicaland physical analysis is available from B.E. Ceological Eurveyoffices in many ma+or cities #Again, 'ong >ongs situationD$


Water


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Heat Pump 19

'eat exchangers may also be submerged in open ponds, lakes, orstreams.

3hen surface or stream water is used as a source, the temperaturedrop across the evaporator in winter may need to be limited toprevent free)e-up.

In industrial applications, waste process water #e.g., spent warm

water in laundries, plant effluent, and warm condenser water$ maybe a heat source for heat pump operation.

Eewage, which often has temperatures higher than that of surface

or groundwater, may be an acceptable heat source.

Eecondary effluent #treated sewage$ is usually preferred, butuntreated sewage may used successfully with proper heatexchanger design.

Water



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Heat Pump 20

he ground is used extensively as a heat source and sink, with heattransfer through buried coils.

Eoil composition, which varies widely from wet clay to sandy soil, hasa predominant effect on thermal properties and expected overallperformance. he heat transfer process in soil depends on transient

heat flow.

hermal diffusivity is a dominant factor and is difficult todetermine without local soil data.

hermal diffusivity is the ratio of thermal conductivity to theproduct of density and specific heat.

he soil moisture content influences its thermal conductivity.


3round


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Heat Pump 21

Eolar energy may be used either as the primary heat source or incombination with other sources.

Air, surface water, shallow groundwater, and shallow ground-source

systems all use solar energy indirectly.

Bsing solar energy directly as a heat source for heat pumps canprovide heat at a higher temperature than the indirect sources,resulting in an increase in the heating coefficient of performance.

4ompared to solar heating without a heat pump, the collectorefficiency and capacity are increased because a lower collectortemperature is re!uired.

Solar Energ'



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Heat Pump 22

here are two basic types of solar-source heat pumps systems F directand indirect.


Solar Energ'

he direct system places refrigerant evaporator tubes in a solarcollector, usually a flat-plate type. A collector without glass coverplates can also extract heat from the outdoor air.

he same surface may then serve as a condenser using outdoor airas a heat sink for cooling.

Direct


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Heat Pump 23

Indirect s'stem

An indirect system circulates either water or air throughthe solar collector.

3hen air is used, the collector may be controlled in such away that :

he collector can serve as an outdoor airpreheater,

he outdoor air loop can be closed so that allsource heat is derived from the sun, or

he collector can be disconnected from theoutdoor air serving as the source or sink.

Solar Energ'



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Heat Pump 24

In an air-source heat pump system, outdoor air acts as a heat sourcefrom which heat is extracted during heating, and as a heat sin.towhich heat is re+ected during cooling.

Eince air is readily available everywhere, air-source heat pumps arethe most widely used heat pumps in residential and man' commercial!uildings.

he cooling capacity of most air-source heat pumps is between / and8; tons #8. and /; k3$.

Air-source heat pumps can be classified as individual room heat pumps

and packaged heat pumps.

Individual room heat pumpsserve only one room without ductwork.

Pac.aged heat pumpscan be subdivided into roo"top heat pumpsandsplit heat pumps%

/I(S-(&E HE/) PMP S4S)EMS 5/irto/ir Heat Pumps


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Heat Pump 25

Eplit Eystem 'eat 6ump&oof top package unit



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Heat Pump 26

4oils through which air isconditioned,

5utdoor Eingle or multiplecompressors,

Indoor coils where heat is extracted

from or re+ected to the outdoor air, 9xpansion valve

&eversing valves that change theheating operation to a coolingoperation and vice versa,

An accumulator to store li!uidrefrigerant, and other accessories.

%ost air-source heat pumps consist of :



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Heat Pump 27

In an air-source heat pump, the indoor coil is not necessarily locatedinside the building.

he indoor coil in a rooftop packaged heat pump is mounted on therooftop.

Gut, an indoor coil always heats and cools the indoor supply air.

*uring cooling operation, the indoor coil acts as an evaporator. It provides the refrigeration effect to cool the mixture of outdoor and

re-circulating air when the heat pump is operating in the re-circulatingmode.

*uring heating operation, the indoor coil acts as a condenser.

he heat re+ected from the condenser raises the temperature of theconditioned supply air.

(or heat pumps using halocarbon refrigerants, the indoor coil is usuallymade from copper tubing and corrugated aluminum fins.

Indoor &oil



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Heat Pump 28

he outdoor coil acts as a condenser during cooling and as anevaporator to extract heat from the outdoor atmosphere duringheating.

3hen an outdoor coil is used as a condenser, a series-connected

subcooling coil often subcools the refrigerant for better systemperformance.

An outdoor coil always deals with outdoor air, whether it acts as acondenser or an evaporator.

Hike the indoor coil, an outdoor coil is usually made of coppertubing and aluminum fins for halocarbon refrigerants.

6late or spine fins are often used instead of corrugated fins toavoid clogging by dust and foreign matter.

-utdoor &oil



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Heat Pump 29

&eversing valves are used to guide the direction of refrigerant flowwhen cooling operation is changed over to heating operation or viceversa.

he rearrangement of the connections between four ways of flowFcompressor suction, compressor discharge, evaporator outlet, andcondenser inletFcauses the functions of the indoor and outdoorcoils to reverse. It is also called a four-way reversing valve.

he efficiency losses altogether with leakage, heat transfer, and

the pressure drop across the reversing valve cause a decrease of to percent in heat pump performance.

5ther accessories include filter dryer, sight glass, strainer, li!uidlevel indicator, solenoid valves, and manual shutoff valves.

(eversing *alve

&eciprocating and scroll compressors are widely used in heat pumps.

&ompressor%



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Heat Pump 30

E,pansion Device

A variety of expansion devices may be used in heat pumps.

he most common types are thermal expansion valves #J$, electronicexpansion valves, and capillary tubes.

All of these devices reduce the pressure and temperature of therefrigerant within the cycle.

9xpansion valves, such as the J, have the added capability of metering

the !uantity of refrigerant flowing through the cycle in order to match theload to enhance the efficiency of the cycle.

Js used in heat pumps may be bi-directional #that is, refrigerant flowsin one direction when in cooling mode and in the opposite direction when inheating mode$.

Another way is to design the refrigerant piping inside the heat pump to

ensure that refrigerant flow through the valve is in the same direction ineither mode.



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Heat Pump 31

3hen the discharge air temperature sensor detects an increase inthe air temperature above a predetermined limit at the exit of theindoor coil, cooling is re!uired in the air-source heat pump.

he indoor coil now acts as an evaporator and extracts heat from theconditioned air flowing through the indoor coil.

After evaporation, vapor refrigerant from the indoor coil passesthrough the sliding connector of the slide and flows to the suctionline.

'ot gas discharged from the compressor is led to the outdoor coil,which now acts as a condenser.

An economi)er cycle can be used when an outdoor air sensor detectsthe outdoor temperature dropping below a specific limit duringcooling mode.

&ooling Mode



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Heat Pump 32

3hen the discharge air sensor detects a drop in airtemperature below a predetermined limit at the exit of theindoor coil, heating is re!uired.

he outdoor coil now acts as an evaporator.

3hen the discharge air temperature sensor detects a drop inair temperature further below preset limits, the electricheater 5that is supplementar' heater$ would be energi)ed insteps to maintain the re!uired discharge air temperature.

Heating Mode



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Heat Pump 33

Supplementar' heatingis energi)ed only when the spaceheating load cannot be offset by the heating effect of the heatpump.

/SH(/E7IES1/ Standard 0%99stipulates heat pumps

e!uipped with internal electrical resistance heaters shall havecontrols to prevent supplemental heater operation when the

heating load can be met by the heat pump alone during heating

or setbackrecovery.

Heating Mode



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Heat Pump 34

(or split packaged air-source heat pumps, indoor coils are locatedinside the building and outdoor coils are mounted outdoors.

3hen an on2off control is used for the compressor, during the offperiod, refrigerant tends to migrate from the warmer outdoor coil

to the cooler indoor coil in summer and from the warmer indoorcoil to the cooler outdoor coil during winter.

3hen the compressor starts again, the transient stateperformance shows that a 7- to -min operating period of reducedcapacity is re!uired before the heat pump can operate at fullcapacity.

Euch a loss due to cycling of the compressor is called cycling loss.

&'cling :oss and Degradation ;actor



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Heat Pump 35

hese heat pumps rely on water as the heat source and sink, and useair to transmit heat to, or from, the conditioned space. hey includethe following:96 3round#ater heat pumps


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Heat Pump 36

hey use surface water from either a lake, pond, orstream as a heat source or sink.

Eimilar to the ground-coupled and groundwater heat

pumps, these systems can either circulate the sourcewater directly to the heat pump or use an intermediatefluid in a closed loop.

Waterto/ir Heat Pumps

3round#ater heat pumps

hey use groundwater from wells as a heat source and2orsink.

hese systems can either circulate the source waterdirectly to the heat pump or use an intermediate fluid in aclosed loop, similar to the ground-coupled heat pump.

Sur"ace #ater heat pumps


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Heat Pump 37

hey use the high internal cooling load generated in modernbuildings either directly or with storage.

hese include water loop heat pumps.


Internalsource heat pumps

hey rely on low-temperature solar heat as the heat source.

Eolar heat pumps may resemble water-to air, or other types,depending on the form of solar heat collector and the type ofheating and cooling distribution system.

Solarassisted heat pumps


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Heat Pump 38

hey use sanitary waste heat or laundry waste heat as a heatsource.

he waste fluid can be introduced directly into the heat pumpevaporator after waste filtration, or it can be taken from astorage tank, depending on the application.

An intermediate loop may also be used for heat transfer betweenthe evaporator and the waste heat source.


Waste#atersource heat pumps


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Heat Pump 39

hese heat pumps use water as the heat source and sink for cooling andheating.

'eating-cooling changeover can be done in the refrigerant circuit, but itis often more convenient to perform the switching in the water circuits.

*irect admittance of the water source to the evaporator is oneapproach.

Alternatively, applying the water source indirectly through a heatexchanger #or double-wall evaporator$ to avoid contaminating the closedchilled water system, which is normally treated may be necessary.

WatertoWater Heat Pumps


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Heat Pump 40

hese use the ground as a heat source and sink.

A heat pump may have a refrigerant-to-water heat exchanger ormay be of the direct-expansion #*J$ type.

In systems with refrigerant-to-water heat exchangers, a water or

antifree)e solution is pumped through hori)ontal, vertical, orcoiled pipes embedded in the ground.

3round&oupled Heat Pumps%


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Heat Pump 41

*irect expansion ground-coupled heat pumps use refrigerant indirect expansion, or flooded evaporator circuits for the groundpipe coils.

3round&oupled Heat Pumps


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Heat Pump 42

Eoil type,moisture content, composition, density, anduniformity close to the surrounding field areas affect thesuccess of this method of heat exchange.

3ith some piping materials, the material of constructionfor the pipe and the corrosiveness of the local soil andunderground water may affect the heat transfer andservice life.

In a variation of this cycle, all or part of the heat fromthe evaporator plus the heat of compression aretransferred to a water-cooled condenser.

his condenser heat is then available for uses such asheating air or domestic hot water.

3round&oupled Heat Pumps


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Heat Pump 43

It may be a tube-in-tube, tube-in-shell, or bra)ed-plate design.

he example shown here is a tube-in-tube, or coaxial, heatexchanger.

It is constructed as a small tube running inside another larger tube.

he water flows through the inner tube and refrigerant flowsthrough the outer tube.

In the cooling mode, the refrigerant-to-water heat exchanger actsas the condenser.

he water flowing through the inner tube absorbs heat from therefrigerant flowing through the outer tube.

In the heating mode, it acts as the evaporator and the refrigerantabsorbs heat from the water.

(e"rigerantto#ater heat e,changer


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Heat Pump 44

In the heat recovery mode 0K saves energy by reducing the operating

time of the cooling tower and boiler.

Allowing different space temperature in many spaces with dissimilar

cooling and heating re!uirements #each independently controlled space

is served by its own heat pump and own thermostat$.

he same piece of e!uipment is used to provide both cooling and heating

to the space. 9ven though a separate cooling tower and boiler may beincluded in the system, only one set of water pipes is re!uired. his can

reduce the system installation cost.

A water-source heat pump system typically re!uires less mechanical

floor space than centrali)ed systems. his increases the rentable space

and revenue in tenant-occupied buildings. If one heat pump fails and must be replaced, it does not affect the

operation of the rest of the system.

Bene"its o" using #atersource heat pump


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Heat Pump 45

5utdoor air for ventilation may bring a few challenges. %ost

commercial buildings have a separate, ducted ventilation

system.

Lext, because a heat pump is located in, or very close to, the

occupied space and contains both a compressor and a fan, the

resulting noise level in the space must be considered during

system design.

6roper maintenance of the heat pumps re!uires that they be

located in accessi!le areas. Bnits that make access as easy as

possible increases the chance that the e!uipment will beproperly maintained.

2e' issues associated #ith #ater source heatpump s'stem%


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Heat Pump 46

'ori)ontal units are designed for installation in ceiling plenums,

especially for spaces where floor space is at a premium.

ypical applications include offices and schools.

Watersource heat pumps&on"igurations

Hori=ontal units

4onfigurations available to suit various building types.


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Heat Pump 47

*ertical units

ertical units are designed to be installed in separate spacessuch as closets or maintenance rooms.

4ommon applications for small vertical units include schools,apartments, condominiums, and retirement homes.

Harger vertical units are generally used in spaces that aremore open, such as cafeterias and gymnasiums, or used as a

dedicated ventilation system to condition the outdoor airbrought into the building.

Watersource heat pumps


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Heat Pump 48

hey are designed for installation under windows, inperimeter spaces or in entryways, where ducted systemscannot be used and floor space is not a constraint.

ypical applications include offices, apartment buildings,motels, and dormitories.

Gecause of their rugged design, they are typically used inschools.

&onsole units



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Heat Pump 49

hey are designed for corner installation in multistorybuildings such as hotels, apartments, condominiums, andretirement centers, where a minimum amount of floorspace is available.

hey are designed to be stacked above each other tominimi)e piping and electrical installation costs.

*erticalstac. units



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Heat Pump 50

'eat adder M re+ecter

Bse of water to water heat pumpCround loop



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Heat Pump 52

*uring cold weather, when most of the heat pumps are operatingin heating mode, heat is removed from the water loop andtransferred to the air.

his causes the temperature of the water in the loop to drop,

making it necessary to add heat to the water loop. A boiler or water heater adds heat to the water loop,

maintaining a leaving-water temperature of approximately /=N4.

&old #eather


-perating strateg'

W t h t


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Heat Pump 53

*uring mild weather, such as spring and fall, the heat pumps servingthe sunny side and interior of the building operate in cooling mode andre+ect heat into the water loop.

he heat pumps serving the shady side of the building operate inheating mode and absorb heat from the water loop.

'eat re+ected by the units operating in cooling mode can be used tooffset the heat absorbed by the units in heating mode.

If the water temperature stays between /=N4 and 87N4, neither theboiler nor the cooling tower need to operate.

Bnder this situation, a water-source heat pump system provides a formof heat recovery and an opportunity to save energy.

In case heat generated by lights, people, and office e!uipment mayre!uire year-round cooling in the interior spaces, this heat recoveryfurther reduces boiler operation during the winter months.

Mild Weather


-perating strateg'


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Heat Pump 54

A ground-source heat pump uses the earth as the heat re+ecterand heat adder.

hese systems take advantage of the earths relatively constanttemperature, and use the ground or surface water as the heatre+ecter and heat adder.

Cround-source heat pump systems dont actually get rid of heatFthey store it in the ground for use at a different time.

*uring the summer, the heat pumps absorb heat from the buildingand store it in the ground.

3hen the building re!uires heating, this stored heat can berecaptured from the ground.

In a perfectly balanced system, the amount of heat stored over agiven period of time would e!ual the amount of heat retrieved.

3roundSource Heat Pump S'stems


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Heat Pump 55

In a properly designed ground-source heat pumpsystem, neither cooling tower nor boiler may benecessary that saves initial cost and floor space.

Cround-source heat pump systems offer the potentialfor operating-cost savings when compared to the

traditional cooling-tower-and-boiler system.

'owever, a significant amount is on the installation costof the ground heat exchanger.

Installation re!uires excavation, trenching, or boring,and in some areas there are very few !ualifiedcontractors for installing the ground heat exchanger.



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Heat Pump 56

his system uses a closed system of special, high-density polyethylenepipes that are buried in the ground at a depth that takes advantage of theearths natural heat sink capabilities.

3hen the building cooling load causes the temperature of the water loop torise, heat is transferred from the water, flowing through the buried pipes,to the cooler earth.

4onversely, when the temperature of the water loop begins to fall, thewater flowing through the buried pipes absorbs heat from the earth.

In a properly designed, ground-coupled system, operating and maintenance

costs are low because a cooling tower and boiler are not re!uired in thesystem.

)here are several t'pes o" groundsource s'stems3roundcoupled s'stem



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Heat Pump 57

ertical loops are the most common in commercial applicationsdue to the limited land generally available.

ertical bore holes are drilled to depths of =; to /; m, with adiameter of /; to 7; cm each.

*ertical loops

he pipes that make up the ground heat exchanger can be orientedin a vertical or hori)ontal pattern.

he choice depends on available land, soil conditions, andexcavation costs.

Pipe pattern



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Heat Pump 58

'ori)ontal loops are often considered when ade!uate land is available.'istorically, hori)ontal loops consisted of a single layer of pipe buried inthe ground using a trencher.

Hori=ontal loops



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Heat Pump 59

3ith the limited of land for installation, multiple-layer hori)ontalloops have been adopted.

3hile less land and trenching is re!uired, more total length ofpiping is re!uired compared to a single layer loop.

he pipes are placed in trenches, typically /.O m deep and spaced/.O to .= m apart.

rench length can range from O. to 8. m2k3.

Multiplela'er hori=ontal loops



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Waterto#ater Heat Pump

Bnit Eelection 6rocedure

Determine the s'stem design conditions "or source and loadside5s o" the e>uipment

9ntering li!uid temperatures for the source-side can be-/./o4 to Po4

9ntering li!uid temperatures for the load-side o4 to Po4

De"ine the selection parameters%

9ntering water temperature,

(luid flow rate, and

(luid pressure drop.

Determine unit re>uirements%

otal cooling capacity2total heatingEtaging of capacity to satisfy cooling re!uirements.

6ressure drop reduction through the load-side of multiple units, even when a single unit mightmeet capacity.

Antifree)e will be re!uired in the fluid loop if source-side leaving water temperature fallsbelow /o4.

Documents

MEBS6008 Heat Pump