2.  It is of great importance to keep an animal’s environment conducive for maximum production.  Research has tended to concentrate on genetic improvements to increase milk production and on nutrient supply to the cow during early lactation.  Excess heat in animal houses can be removed using a heat pump.

3.  Most of the heat produced by animals is usually left hanging around the animal making it uncomfortable and affecting its productivity.  Even with ventilation to cool the animal, the heat would still be wasted yet it could be recovered for reheat purposes.

4. Overall objective  To design a heat recovery system for an animal house using a heat pump. Specific objectives  To determine how much heat is produced by a cattle unit housing 200 cattle.  To analyze a heat pump to recover this heat energy  To determine how much heat is recovered from the system and suggest areas where this heat can be used.

5.  Area - 30m by 15m with a height of 3m.  Intended holding capacity - 200 Friesian cows  current capacity - 60 cows  Weight per cow - 400kg.  Existing structure is made of concrete, with an open upper half.  Temperatures of up to 27 0 C, with the coldest months as June, July and part of August with temperatures as low as 14 0 C.

7.  Energy recovery is a common practice in countries looking to sustainable ways of maintaining cost effective heating and cooling systems.  Denmark uses centralized heating and cooling systems to lower costs and reduce emissions, with uniquely developed solutions to enable sustainable district heating and cooling. (www.stateofgreen.htm)

8.  Hot water production with a Primary goal to make available a supply of hot water  Heat recovery for hot water production: Aimed at reducing heating costs by heating water with waste heat recovered from an overheated area which does not otherwise require cooling  Heat recovery for space cooling: Employed to cool a space, typically for comfort or product storage and also reduce heating costs by reducing the load on boilers

9.  Mechanical ventilation with heat recovery (MVHR) systems exchange stale air for fresh air, and recover heat in the process.  A heat recovery ventilator is a device that extracts heat that would normally be expelled to the atmosphere and transferring this heat to another location like fresh air before it is redistributed.

10.  A heat pump is a machine or device that moves heat from one location (the 'source'),at a lower temperature, to another location (the 'sink'),at a higher temperature, using mechanical work.

11. (Cengel and Michael, 2008)

12. Several factors are considered during the design process, they include;  The climate characteristics of the place where it will be installed e.g. temperature  The type of building i.e. residential, tertiary or industrial buildings.  Conditions of usage.  Amount of heat to be produced from the source.

13.  Heat produced by animals  Refrigerant choice  Heat pump analysis  Amount of energy used by heat pump  Energy produced by heat ump

14.  Determination of heat produced by the animals per unit weight, Q s. Q s = N *sensible heat produced per animal*unit weight = 54.8MW  Determination of condenser pressures and operation temperatures Condenser temperatures should be at least 10°C higher than ambient temperatures

15. @ 0.2 bar and 1bar pressures At 25 0 C and 0 0 C temperatures Q H heat extracted from heat pump (KJ/Kg) 155.37KJ/Kg172.88KJ/Kg ΔΘ of water at condenser 7.48.3 COP 3.134.03 Compressor power (KW) 36.726

16.  The heat pump would recover up to172.88KJ/Kg from an input 26KW  137KJ/Kg heat is produced by a cattle unit housing 200 cattle  The amount of heat recovered from the system would be 172.88KJ/Kg.  This heat can be used around the farm for cleaning purposes, or expelled from the condenser directly to a calf pen.

17.  Consider use of a heat pump with vapor injection to allow for reheat of the refrigerant. As it delivers a higher temperature at the condenser and raises the COP of the system.  A modification of the ventilation system would also provide for easier heat recovery from the animal house.

18.  American Society of Agricultural and Biological Engineers (ASABE) 2009 ASABE standards. St. Joseph, Michigan, USA.  American Society of Heating, Refrigeration and Air-conditioning Engineers (ASHRAE). 2005. ASHRAE Handbook of fundamentals  Cengel, Y.A. & Michael, A.B. (2008). Thermodynamics: An Engineering Approach 6 th Ed. McGraw Hill Inc.  Eastop, T.D. & McConkey, A. (2009). Application Thermodynamics for Engineering Technologists. 5 th Ed. Pearson publication.

19.  Haines, R.W. & Wilson, C.L. 1994. HVAC systems design handbook. New York, USA, McGraw Hill Inc.  Hellickson, M.A. & Walker, J.N. Ventilation of Agricultural Structures. ASAE monograph No. 6. St. Joseph, Michigan, USA.  Kreider, J.F. 2001. Handbook of heating, ventilation and air conditioning. Boca Raton, Florida, USA. CRC Press Ltd.  Wang, S.K. 2000. Handbook of air conditioning and refrigeration. New York, McGraw Hill Inc.  www.heatpumpcentre.org www.heatpumpcentre.org  www.stateofgreen.htm www.stateofgreen.htm