1. Heather Instasi Tulio Borel

2. Objectives Design a radiant heating system for a greenhouse located in Atascadero, CA Hot ethylene-glycol solution flowing in tubes embedded in 20ft x 40 ft concrete foundation Keep greenhouse air around 68 °F

3. Process Calculate heat loads based on greenhouse geometry Select spacing and diameter of tubing and number of coils 2D conduction model Find heat transfer, flow rate, temperatures, pressure drop in each coil Find total pressure drop Select a pump, heat exchanger, boiler, expansion tank Cost estimation

4. 2D Conduction Model Things to consider: Pressure drop Cost Even heating

5. System Layout Drawing

6. Total System Pressure Drop Include: Heat Exchanger Pressure Drop (2.42 lbf/in 2 ) Pressure drop due to fittings (elbows & tees—branch and line flow) (0.1196 lbf/in 2 ) Pressure drop in each coil (3.715 lbf/in 2 ) Pressure drop in pipe connecting mechanical room & greenhouse (1.1494 lbf/in 2 ) Pressure drop between boiler and heat exchanger in mechanical room (0.028 lbf/in 2 ) Total = 7.432 lbf/in 2

7. Pump Selection Operating Point: 6.368 gpm 17.17 ft of Head

8. Heat Exchanger Selection Need at least 48972 Btu/hr heat transfer rate SEC PL/PLT 70 Heat Exchanger produces 52208 Btu/hr Temperature difference of 15.5 °R on boiler side Flow Rate 3373 lbm/hr (25L/min)

9. Boiler Selection Utica MGB-125J Input Rate: 125000Btu/hr Heating Capacity: 104000Btu/hr Efficiency: 82% Bypass flow rate: 6.683 gpm

10. Expansion Tank Selection Flexcon 2.1 gallon tank Total volume needed = 0.4098 gallons

11. Cost Analysis Total capital cost: $13172 Insulation cost Operating Costs Boiler: $3321/yr Pump: $19.44/yr Present worth analysis for 15 years at 6% interest rate: $45,613 Electric system PW analysis: $85163 Electric system is 86% more expensive Insulation Thickness (in) Area of Insulation (ft^2) Heat Transfer Loss (Btu/hr) Capital Cost ($) Operating Cost in a year ($/yr) O.C in 15 year Life Cycle ($) 180012729856338.23284 2160063641712169.11642 3240042432568112.71095 432003182342484.53821 540002546428067.64656.9 Figure 1: Insulation Cost Analysis