How do i connect chilled water supply pipes and return pipes?

Depending on what sorts of fittings are furnished on this manufactured equipment (threaded, flanged, grooved, etc.), select matching fittings to connect them. If dissimilar metals are involved, you may need dielectric fittings (which have various gaskets, bolt sleeves and washers, and the like, to separate the unmatched metals).

If you are talking about the topology of what attaches to what, there should be a P&ID (piping and instrumentation drawing) to detail that. If not, you will need someone to design it.

If your question is "what goes where?"- here is a general guideline

Chilled water should be "pushed" into the chiller so that pump energy is removed.

Cooling tower water, assuming "open" tower must be pulled from tower and pushed into chiller. If tower is "closed"- spray and air over coils that contain the cooling water- it is better to push water into tower (again to remove pump heat).

Air handlers will be on the downstream side of the chiller, fed from bottom, front and discharging from top, rear (air inlet side) of coils. Ideally, you should use a 2-port valve (restricting flow) on the discharge of the coil. The discharge location assures that the coil is always under pressure and minimizes formation of air bubbles that can reduce coil performance.

If you have several air handlers or highly variable flow, the best option is a primary-secondary piping system where the primary flow is constant into the chiller and then returning to the inlet of the pump. This flow should be sized based on a relatively high delta-T (say 44F leaving the chiller and 60F (or higher) returning to the chiller to minimize the horsepower load. The secondary pump extracts water from the primary main and sends it to the AHUs. This pump operates on a variable flow, designed to maintain a differential pressure between the supply and the return, that responds to the position of the control valves, which respond to thermostats in the space or supply air temperature. The return connection to the primary main is within 2 feet of the discharge connection. The close connection is in case the AHU flow is higher than the chiller flow (possible). The excess flow causes the water in the chiller main to flow "backwards" within the 2 feet between the branch main connections without disrupting overall flow- say 120 GPM in the AHU branch and 100 GPM in the chiller main- 100 GPM goes up to the secondary outlet, 120 comes back from the AHU and 20 goes backwards to let 120 go out to the AHU (a little warmer than the chiller discharge) while the remaining 100 GPM of the return goes on back to the chiller.

Some people believe that you can eliminate the dual piping and use just the primary loop for all of the chilled water system, but you must be sure that adequate flow is maintained in the chiller under low load (to avoid unintended freeze-up). If you use this type of single pump system, you should include some form of bypass/bleed valve to make sure that adequate flow is always present- possibly triggered by a differential pressure meter across the discharge and return mains to open to maintain some maximum pressure differential.

Hope this helps.